29 files changed, 277 insertions, 84 deletions

diff --git a/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h b/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h
index e5f924c8..c2641b5f 100644
--- a/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h
+++ b/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h
@@ -38,6 +38,13 @@ enum BOOTSTRAPPER_ERROR_TYPE
     BOOTSTRAPPER_ERROR_TYPE_APPLY,              // error occurred during apply.
 };
 
+enum BOOTSTRAPPER_FILES_IN_USE_TYPE
+{
+    BOOTSTRAPPER_FILES_IN_USE_TYPE_MSI,    // INSTALLMESSAGE_FILESINUSE
+    BOOTSTRAPPER_FILES_IN_USE_TYPE_MSI_RM, // INSTALLMESSAGE_RMFILESINUSE
+    BOOTSTRAPPER_FILES_IN_USE_TYPE_NETFX,  // MMIO_CLOSE_APPS
+};
+
 enum BOOTSTRAPPER_RELATED_OPERATION
 {
     BOOTSTRAPPER_RELATED_OPERATION_NONE,
@@ -874,6 +881,7 @@ struct BA_ONEXECUTEFILESINUSE_ARGS
     DWORD cFiles;
     LPCWSTR* rgwzFiles;
     int nRecommendation;
+    BOOTSTRAPPER_FILES_IN_USE_TYPE source;
 };
 
 struct BA_ONEXECUTEFILESINUSE_RESULTS
diff --git a/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs b/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs
index a78bf43f..b1fcaea4 100644
--- a/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs
+++ b/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs
@@ -1712,9 +1712,9 @@ namespace WixToolset.Mba.Core
             return args.HResult;
         }
 
-        int IBootstrapperApplication.OnExecuteFilesInUse(string wzPackageId, int cFiles, string[] rgwzFiles, Result nRecommendation, ref Result pResult)
+        int IBootstrapperApplication.OnExecuteFilesInUse(string wzPackageId, int cFiles, string[] rgwzFiles, Result nRecommendation, FilesInUseType source, ref Result pResult)
         {
-            ExecuteFilesInUseEventArgs args = new ExecuteFilesInUseEventArgs(wzPackageId, rgwzFiles, nRecommendation, pResult);
+            ExecuteFilesInUseEventArgs args = new ExecuteFilesInUseEventArgs(wzPackageId, rgwzFiles, nRecommendation, source, pResult);
             this.OnExecuteFilesInUse(args);
 
             pResult = args.Result;
diff --git a/src/api/burn/WixToolset.Mba.Core/EventArgs.cs b/src/api/burn/WixToolset.Mba.Core/EventArgs.cs
index 55c9e74c..65169b25 100644
--- a/src/api/burn/WixToolset.Mba.Core/EventArgs.cs
+++ b/src/api/burn/WixToolset.Mba.Core/EventArgs.cs
@@ -1613,11 +1613,12 @@ namespace WixToolset.Mba.Core
     public class ExecuteFilesInUseEventArgs : ResultEventArgs
     {
         /// <summary />
-        public ExecuteFilesInUseEventArgs(string packageId, string[] files, Result recommendation, Result result)
+        public ExecuteFilesInUseEventArgs(string packageId, string[] files, Result recommendation, FilesInUseType source, Result result)
             : base(recommendation, result)
         {
             this.PackageId = packageId;
             this.Files = new ReadOnlyCollection<string>(files ?? new string[] { });
+            this.Source = source;
         }
 
         /// <summary>
@@ -1629,6 +1630,11 @@ namespace WixToolset.Mba.Core
         /// Gets the list of files in use.
         /// </summary>
         public IList<string> Files { get; private set; }
+
+        /// <summary>
+        /// Gets the source of the message.
+        /// </summary>
+        public FilesInUseType Source { get; private set; }
     }
 
     /// <summary>
diff --git a/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs b/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs
index c6a8fc14..3df54bde 100644
--- a/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs
+++ b/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs
@@ -777,12 +777,6 @@ namespace WixToolset.Mba.Core
         /// <summary>
         /// See <see cref="IDefaultBootstrapperApplication.ExecuteFilesInUse"/>.
         /// </summary>
-        /// <param name="wzPackageId"></param>
-        /// <param name="cFiles"></param>
-        /// <param name="rgwzFiles"></param>
-        /// <param name="nRecommendation"></param>
-        /// <param name="pResult"></param>
-        /// <returns></returns>
         [PreserveSig]
         [return: MarshalAs(UnmanagedType.I4)]
         int OnExecuteFilesInUse(
@@ -790,6 +784,7 @@ namespace WixToolset.Mba.Core
             [MarshalAs(UnmanagedType.U4)] int cFiles,
             [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1, ArraySubType = UnmanagedType.LPWStr), In] string[] rgwzFiles,
             [MarshalAs(UnmanagedType.I4)] Result nRecommendation,
+            [MarshalAs(UnmanagedType.I4)] FilesInUseType source,
             [MarshalAs(UnmanagedType.I4)] ref Result pResult
             );
 
@@ -1446,6 +1441,25 @@ namespace WixToolset.Mba.Core
     };
 
     /// <summary>
+    /// Indicates the source of the FilesInUse message.
+    /// </summary>
+    public enum FilesInUseType
+    {
+        /// <summary>
+        /// Generated from INSTALLMESSAGE_FILESINUSE.
+        /// </summary>
+        Msi,
+        /// <summary>
+        /// Generated from INSTALLMESSAGE_RMFILESINUSE.
+        /// </summary>
+        MsiRm,
+        /// <summary>
+        /// Generated from MMIO_CLOSE_APPS.
+        /// </summary>
+        Netfx,
+    }
+
+    /// <summary>
     /// The calculated operation for the related bundle.
     /// </summary>
     public enum RelatedOperation
diff --git a/src/api/burn/balutil/inc/BalBaseBAFunctions.h b/src/api/burn/balutil/inc/BalBaseBAFunctions.h
index 8d9bddca..7f52f76e 100644
--- a/src/api/burn/balutil/inc/BalBaseBAFunctions.h
+++ b/src/api/burn/balutil/inc/BalBaseBAFunctions.h
@@ -583,6 +583,7 @@ public: // IBootstrapperApplication
         __in DWORD /*cFiles*/,
         __in_ecount_z(cFiles) LPCWSTR* /*rgwzFiles*/,
         __in int /*nRecommendation*/,
+        __in BOOTSTRAPPER_FILES_IN_USE_TYPE /*source*/,
         __inout int* /*pResult*/
         )
     {
diff --git a/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h b/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
index 4d043dfe..5665fee3 100644
--- a/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
+++ b/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
@@ -738,6 +738,7 @@ public: // IBootstrapperApplication
         __in DWORD /*cFiles*/,
         __in_ecount_z(cFiles) LPCWSTR* /*rgwzFiles*/,
         __in int /*nRecommendation*/,
+        __in BOOTSTRAPPER_FILES_IN_USE_TYPE /*source*/,
         __inout int* pResult
         )
     {
diff --git a/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h b/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h
index 59bfc1f8..2292cd64 100644
--- a/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h
+++ b/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h
@@ -438,7 +438,7 @@ static HRESULT BalBaseBAProcOnExecuteFilesInUse(
     __inout BA_ONEXECUTEFILESINUSE_RESULTS* pResults
     )
 {
-    return pBA->OnExecuteFilesInUse(pArgs->wzPackageId, pArgs->cFiles, pArgs->rgwzFiles, pArgs->nRecommendation, &pResults->nResult);
+    return pBA->OnExecuteFilesInUse(pArgs->wzPackageId, pArgs->cFiles, pArgs->rgwzFiles, pArgs->nRecommendation, pArgs->source, &pResults->nResult);
 }
 
 static HRESULT BalBaseBAProcOnExecutePackageComplete(
diff --git a/src/api/burn/balutil/inc/IBootstrapperApplication.h b/src/api/burn/balutil/inc/IBootstrapperApplication.h
index be9b7b6e..2ba1f503 100644
--- a/src/api/burn/balutil/inc/IBootstrapperApplication.h
+++ b/src/api/burn/balutil/inc/IBootstrapperApplication.h
@@ -488,27 +488,19 @@ DECLARE_INTERFACE_IID_(IBootstrapperApplication, IUnknown, "53C31D56-49C0-426B-A
         __inout int* pResult
         ) = 0;
 
-    // OnExecuteFilesInUse - called when the engine encounters files in use while
-    //                       executing a package.
+    // OnExecuteFilesInUse - called when the engine receives a files in use message
+    //                       while executing a package.
     //
-    // Return:
-    //  IDOK instructs the engine to let the Restart Manager attempt to close the
-    //       applications to avoid a restart.
-    //
-    //  IDCANCEL instructs the engine to abort the execution and start rollback.
-    //
-    //  IDIGNORE instructs the engine to ignore the running applications. A restart will be
-    //           required.
-    //
-    //  IDRETRY instructs the engine to check if the applications are still running again.
-    //
-    //  IDNOACTION is equivalent to ignoring the running applications. A restart will be
-    //             required.
+    // Return value depends on the source:
+    //  BOOTSTRAPPER_FILES_IN_USE_TYPE_MSI: https://docs.microsoft.com/en-us/windows/win32/msi/installvalidate-action
+    //  BOOTSTRAPPER_FILES_IN_USE_TYPE_MSI_RM: https://docs.microsoft.com/en-us/windows/win32/msi/using-restart-manager-with-an-external-ui-
+    //  BOOTSTRAPPER_FILES_IN_USE_TYPE_NETFX: https://docs.microsoft.com/en-us/dotnet/framework/deployment/how-to-get-progress-from-the-dotnet-installer
     STDMETHOD(OnExecuteFilesInUse)(
         __in_z LPCWSTR wzPackageId,
         __in DWORD cFiles,
         __in_ecount_z(cFiles) LPCWSTR* rgwzFiles,
         __in int nRecommendation,
+        __in BOOTSTRAPPER_FILES_IN_USE_TYPE source,
         __inout int* pResult
         ) = 0;
 
diff --git a/src/burn/engine/apply.cpp b/src/burn/engine/apply.cpp
index dfaba3f2..9e552ee0 100644
--- a/src/burn/engine/apply.cpp
+++ b/src/burn/engine/apply.cpp
@@ -1931,8 +1931,8 @@ static HRESULT WINAPI AuthenticationRequired(
 
     APPLY_AUTHENTICATION_REQUIRED_DATA* authenticationData = reinterpret_cast<APPLY_AUTHENTICATION_REQUIRED_DATA*>(pData);
 
-    UserExperienceOnError(authenticationData->pUX, errorType, authenticationData->wzPackageOrContainerId, ERROR_ACCESS_DENIED, sczError, MB_RETRYTRYAGAIN, 0, NULL, &nResult); // ignore return value;
-    nResult = UserExperienceCheckExecuteResult(authenticationData->pUX, FALSE, MB_RETRYTRYAGAIN, nResult);
+    UserExperienceOnError(authenticationData->pUX, errorType, authenticationData->wzPackageOrContainerId, ERROR_ACCESS_DENIED, sczError, MB_RETRYCANCEL, 0, NULL, &nResult); // ignore return value;
+    nResult = UserExperienceCheckExecuteResult(authenticationData->pUX, FALSE, BURN_MB_RETRYTRYAGAIN, nResult);
     if (IDTRYAGAIN == nResult && authenticationData->pUX->hwndApply)
     {
         er = ::InternetErrorDlg(authenticationData->pUX->hwndApply, hUrl, ERROR_INTERNET_INCORRECT_PASSWORD, FLAGS_ERROR_UI_FILTER_FOR_ERRORS | FLAGS_ERROR_UI_FLAGS_CHANGE_OPTIONS | FLAGS_ERROR_UI_FLAGS_GENERATE_DATA, NULL);
@@ -2495,10 +2495,10 @@ static HRESULT ExecuteExePackage(
     ExitOnRootFailure(hr, "BA aborted execute EXE package begin.");
 
     message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
     message.progress.dwPercentage = fRollback ? 100 : 0;
     nResult = GenericExecuteMessageHandler(&message, pContext);
-    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwAllowedResults, nResult);
+    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwUIHint, nResult);
     ExitOnRootFailure(hr, "BA aborted EXE progress.");
 
     fExecuted = TRUE;
@@ -2516,10 +2516,10 @@ static HRESULT ExecuteExePackage(
     }
 
     message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
     message.progress.dwPercentage = fRollback ? 0 : 100;
     nResult = GenericExecuteMessageHandler(&message, pContext);
-    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwAllowedResults, nResult);
+    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwUIHint, nResult);
     ExitOnRootFailure(hr, "BA aborted EXE progress.");
 
     pContext->cExecutedPackages += fRollback ? -1 : 1;
@@ -2712,10 +2712,10 @@ static HRESULT ExecuteMsuPackage(
     ExitOnRootFailure(hr, "BA aborted execute MSU package begin.");
 
     message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
     message.progress.dwPercentage = fRollback ? 100 : 0;
     nResult = GenericExecuteMessageHandler(&message, pContext);
-    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwAllowedResults, nResult);
+    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwUIHint, nResult);
     ExitOnRootFailure(hr, "BA aborted MSU progress.");
 
     fExecuted = TRUE;
@@ -2733,10 +2733,10 @@ static HRESULT ExecuteMsuPackage(
     }
 
     message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
     message.progress.dwPercentage = fRollback ? 0 : 100;
     nResult = GenericExecuteMessageHandler(&message, pContext);
-    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwAllowedResults, nResult);
+    hr = UserExperienceInterpretExecuteResult(&pEngineState->userExperience, fRollback, message.dwUIHint, nResult);
     ExitOnRootFailure(hr, "BA aborted MSU progress.");
 
     pContext->cExecutedPackages += fRollback ? -1 : 1;
@@ -3047,6 +3047,7 @@ static int GenericExecuteMessageHandler(
     )
 {
     BURN_EXECUTE_CONTEXT* pContext = (BURN_EXECUTE_CONTEXT*)pvContext;
+    DWORD dwAllowedResults = pMessage->dwUIHint & MB_TYPEMASK;
     int nResult = IDNOACTION;
 
     switch (pMessage->type)
@@ -3059,15 +3060,16 @@ static int GenericExecuteMessageHandler(
         break;
 
     case GENERIC_EXECUTE_MESSAGE_ERROR:
-        UserExperienceOnError(pContext->pUX, BOOTSTRAPPER_ERROR_TYPE_EXE_PACKAGE, pContext->pExecutingPackage->sczId, pMessage->error.dwErrorCode, pMessage->error.wzMessage, pMessage->dwAllowedResults, 0, NULL, &nResult); // ignore return value.
+        UserExperienceOnError(pContext->pUX, BOOTSTRAPPER_ERROR_TYPE_EXE_PACKAGE, pContext->pExecutingPackage->sczId, pMessage->error.dwErrorCode, pMessage->error.wzMessage, pMessage->dwUIHint, 0, NULL, &nResult); // ignore return value.
         break;
 
-    case GENERIC_EXECUTE_MESSAGE_FILES_IN_USE:
-        UserExperienceOnExecuteFilesInUse(pContext->pUX, pContext->pExecutingPackage->sczId, pMessage->filesInUse.cFiles, pMessage->filesInUse.rgwzFiles, &nResult); // ignore return value.
+    case GENERIC_EXECUTE_MESSAGE_NETFX_FILES_IN_USE:
+        UserExperienceOnExecuteFilesInUse(pContext->pUX, pContext->pExecutingPackage->sczId, pMessage->filesInUse.cFiles, pMessage->filesInUse.rgwzFiles, BOOTSTRAPPER_FILES_IN_USE_TYPE_NETFX, &nResult); // ignore return value.
+        dwAllowedResults = BURN_MB_NETFX_FILES_IN_USE;
         break;
     }
 
-    nResult = UserExperienceCheckExecuteResult(pContext->pUX, pContext->fRollback, pMessage->dwAllowedResults, nResult);
+    nResult = UserExperienceCheckExecuteResult(pContext->pUX, pContext->fRollback, dwAllowedResults, nResult);
     return nResult;
 }
 
@@ -3077,7 +3079,9 @@ static int MsiExecuteMessageHandler(
     )
 {
     BURN_EXECUTE_CONTEXT* pContext = (BURN_EXECUTE_CONTEXT*)pvContext;
+    DWORD dwAllowedResults = pMessage->dwUIHint & MB_TYPEMASK;
     int nResult = IDNOACTION;
+    BOOL fRestartManager = FALSE;
 
     switch (pMessage->type)
     {
@@ -3090,20 +3094,24 @@ static int MsiExecuteMessageHandler(
 
     case WIU_MSI_EXECUTE_MESSAGE_ERROR:
         nResult = pMessage->nResultRecommendation;
-        UserExperienceOnError(pContext->pUX, BOOTSTRAPPER_ERROR_TYPE_WINDOWS_INSTALLER, pContext->pExecutingPackage->sczId, pMessage->error.dwErrorCode, pMessage->error.wzMessage, pMessage->dwAllowedResults, pMessage->cData, pMessage->rgwzData, &nResult); // ignore return value.
+        UserExperienceOnError(pContext->pUX, BOOTSTRAPPER_ERROR_TYPE_WINDOWS_INSTALLER, pContext->pExecutingPackage->sczId, pMessage->error.dwErrorCode, pMessage->error.wzMessage, pMessage->dwUIHint, pMessage->cData, pMessage->rgwzData, &nResult); // ignore return value.
         break;
 
     case WIU_MSI_EXECUTE_MESSAGE_MSI_MESSAGE:
         nResult = pMessage->nResultRecommendation;
-        UserExperienceOnExecuteMsiMessage(pContext->pUX, pContext->pExecutingPackage->sczId, pMessage->msiMessage.mt, pMessage->dwAllowedResults, pMessage->msiMessage.wzMessage, pMessage->cData, pMessage->rgwzData, &nResult); // ignore return value.
+        UserExperienceOnExecuteMsiMessage(pContext->pUX, pContext->pExecutingPackage->sczId, pMessage->msiMessage.mt, pMessage->dwUIHint, pMessage->msiMessage.wzMessage, pMessage->cData, pMessage->rgwzData, &nResult); // ignore return value.
         break;
 
+    case WIU_MSI_EXECUTE_MESSAGE_MSI_RM_FILES_IN_USE:
+        fRestartManager = TRUE;
+        __fallthrough;
     case WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE:
-        UserExperienceOnExecuteFilesInUse(pContext->pUX, pContext->pExecutingPackage->sczId, pMessage->msiFilesInUse.cFiles, pMessage->msiFilesInUse.rgwzFiles, &nResult); // ignore return value.
+        UserExperienceOnExecuteFilesInUse(pContext->pUX, pContext->pExecutingPackage->sczId, pMessage->msiFilesInUse.cFiles, pMessage->msiFilesInUse.rgwzFiles, fRestartManager ? BOOTSTRAPPER_FILES_IN_USE_TYPE_MSI_RM : BOOTSTRAPPER_FILES_IN_USE_TYPE_MSI, &nResult); // ignore return value.
+        dwAllowedResults = fRestartManager ? BURN_MB_MSI_RM_FILES_IN_USE : BURN_MB_MSI_FILES_IN_USE;
         break;
     }
 
-    nResult = UserExperienceCheckExecuteResult(pContext->pUX, pContext->fRollback, pMessage->dwAllowedResults, nResult);
+    nResult = UserExperienceCheckExecuteResult(pContext->pUX, pContext->fRollback, dwAllowedResults, nResult);
     return nResult;
 }
 
diff --git a/src/burn/engine/apply.h b/src/burn/engine/apply.h
index 45270f92..1717a71a 100644
--- a/src/burn/engine/apply.h
+++ b/src/burn/engine/apply.h
@@ -12,7 +12,7 @@ enum GENERIC_EXECUTE_MESSAGE_TYPE
     GENERIC_EXECUTE_MESSAGE_NONE,
     GENERIC_EXECUTE_MESSAGE_ERROR,
     GENERIC_EXECUTE_MESSAGE_PROGRESS,
-    GENERIC_EXECUTE_MESSAGE_FILES_IN_USE,
+    GENERIC_EXECUTE_MESSAGE_NETFX_FILES_IN_USE,
 };
 
 typedef struct _APPLY_AUTHENTICATION_REQUIRED_DATA
@@ -25,7 +25,7 @@ typedef struct _APPLY_AUTHENTICATION_REQUIRED_DATA
 typedef struct _GENERIC_EXECUTE_MESSAGE
 {
     GENERIC_EXECUTE_MESSAGE_TYPE type;
-    DWORD dwAllowedResults;
+    DWORD dwUIHint;
 
     union
     {
diff --git a/src/burn/engine/detect.cpp b/src/burn/engine/detect.cpp
index 5f68a240..4eda240e 100644
--- a/src/burn/engine/detect.cpp
+++ b/src/burn/engine/detect.cpp
@@ -306,8 +306,8 @@ static HRESULT WINAPI AuthenticationRequired(
     hr = StrAllocFromError(&sczError, HRESULT_FROM_WIN32(ERROR_ACCESS_DENIED), NULL);
     ExitOnFailure(hr, "Failed to allocation error string.");
 
-    UserExperienceOnError(pAuthenticationData->pUX, errorType, pAuthenticationData->wzPackageOrContainerId, ERROR_ACCESS_DENIED, sczError, MB_RETRYTRYAGAIN, 0, NULL, &nResult); // ignore return value.
-    nResult = UserExperienceCheckExecuteResult(pAuthenticationData->pUX, FALSE, MB_RETRYTRYAGAIN, nResult);
+    UserExperienceOnError(pAuthenticationData->pUX, errorType, pAuthenticationData->wzPackageOrContainerId, ERROR_ACCESS_DENIED, sczError, MB_RETRYCANCEL, 0, NULL, &nResult); // ignore return value.
+    nResult = UserExperienceCheckExecuteResult(pAuthenticationData->pUX, FALSE, BURN_MB_RETRYTRYAGAIN, nResult);
     if (IDTRYAGAIN == nResult && pAuthenticationData->pUX->hwndDetect)
     {
         er = ::InternetErrorDlg(pAuthenticationData->pUX->hwndDetect, hUrl, ERROR_INTERNET_INCORRECT_PASSWORD, FLAGS_ERROR_UI_FILTER_FOR_ERRORS | FLAGS_ERROR_UI_FLAGS_CHANGE_OPTIONS | FLAGS_ERROR_UI_FLAGS_GENERATE_DATA, NULL);
diff --git a/src/burn/engine/elevation.cpp b/src/burn/engine/elevation.cpp
index 12c9f296..6c4a775f 100644
--- a/src/burn/engine/elevation.cpp
+++ b/src/burn/engine/elevation.cpp
@@ -42,7 +42,8 @@ typedef enum _BURN_ELEVATION_MESSAGE_TYPE
     BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_PROGRESS,
     BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_ERROR,
     BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_MSI_MESSAGE,
-    BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_FILES_IN_USE,
+    BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_MSI_FILES_IN_USE,
+    BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_NETFX_FILES_IN_USE,
     BURN_ELEVATION_MESSAGE_TYPE_LAUNCH_APPROVED_EXE_PROCESSID,
     BURN_ELEVATION_MESSAGE_TYPE_PROGRESS_ROUTINE,
 } BURN_ELEVATION_MESSAGE_TYPE;
@@ -1618,7 +1619,7 @@ static HRESULT ProcessGenericExecuteMessages(
     LPWSTR* rgwzFiles = NULL;
     GENERIC_EXECUTE_MESSAGE message = { };
 
-    hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, &message.dwAllowedResults);
+    hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, &message.dwUIHint);
     ExitOnFailure(hr, "Failed to allowed results.");
     
     // Process the message.
@@ -1645,8 +1646,8 @@ static HRESULT ProcessGenericExecuteMessages(
         message.error.wzMessage = sczMessage;
         break;
 
-    case BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_FILES_IN_USE:
-        message.type = GENERIC_EXECUTE_MESSAGE_FILES_IN_USE;
+    case BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_NETFX_FILES_IN_USE:
+        message.type = GENERIC_EXECUTE_MESSAGE_NETFX_FILES_IN_USE;
 
         // read message parameters
         hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, &cFiles);
@@ -1701,6 +1702,7 @@ static HRESULT ProcessMsiPackageMessages(
     LPWSTR* rgwzMsiData = NULL;
     BURN_ELEVATION_MSI_MESSAGE_CONTEXT* pContext = static_cast<BURN_ELEVATION_MSI_MESSAGE_CONTEXT*>(pvContext);
     LPWSTR sczMessage = NULL;
+    BOOL fRestartManager = FALSE;
 
     // Read MSI extended message data.
     hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, &cMsiData);
@@ -1721,7 +1723,7 @@ static HRESULT ProcessMsiPackageMessages(
         message.rgwzData = (LPCWSTR*)rgwzMsiData;
     }
 
-    hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, &message.dwAllowedResults);
+    hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, &message.dwUIHint);
     ExitOnFailure(hr, "Failed to read UI flags.");
 
     // Process the rest of the message.
@@ -1759,8 +1761,11 @@ static HRESULT ProcessMsiPackageMessages(
         message.msiMessage.wzMessage = sczMessage;
         break;
 
-    case BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_FILES_IN_USE:
-        message.type = WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE;
+    case BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_MSI_FILES_IN_USE:
+        hr = BuffReadNumber((BYTE*)pMsg->pvData, pMsg->cbData, &iData, (DWORD*)&fRestartManager);
+        ExitOnFailure(hr, "Failed to read fRestartManager.");
+
+        message.type = fRestartManager ? WIU_MSI_EXECUTE_MESSAGE_MSI_RM_FILES_IN_USE : WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE;
         message.msiFilesInUse.cFiles = cMsiData;
         message.msiFilesInUse.rgwzFiles = (LPCWSTR*)rgwzMsiData;
         break;
@@ -3006,7 +3011,7 @@ static int GenericExecuteMessageHandler(
     SIZE_T cbData = 0;
     DWORD dwMessage = 0;
 
-    hr = BuffWriteNumber(&pbData, &cbData, pMessage->dwAllowedResults);
+    hr = BuffWriteNumber(&pbData, &cbData, pMessage->dwUIHint);
     ExitOnFailure(hr, "Failed to write UI flags.");
 
     switch(pMessage->type)
@@ -3030,7 +3035,7 @@ static int GenericExecuteMessageHandler(
         dwMessage = BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_ERROR;
         break;
 
-    case GENERIC_EXECUTE_MESSAGE_FILES_IN_USE:
+    case GENERIC_EXECUTE_MESSAGE_NETFX_FILES_IN_USE:
         hr = BuffWriteNumber(&pbData, &cbData, pMessage->filesInUse.cFiles);
         ExitOnFailure(hr, "Failed to count of files in use to message buffer.");
 
@@ -3040,7 +3045,7 @@ static int GenericExecuteMessageHandler(
             ExitOnFailure(hr, "Failed to write file in use to message buffer.");
         }
 
-        dwMessage = BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_FILES_IN_USE;
+        dwMessage = BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_NETFX_FILES_IN_USE;
         break;
     }
 
@@ -3065,6 +3070,7 @@ static int MsiExecuteMessageHandler(
     BYTE* pbData = NULL;
     SIZE_T cbData = 0;
     DWORD dwMessage = 0;
+    BOOL fRestartManager = FALSE;
 
     // Always send any extra data via the struct first.
     hr = BuffWriteNumber(&pbData, &cbData, pMessage->cData);
@@ -3076,7 +3082,7 @@ static int MsiExecuteMessageHandler(
         ExitOnFailure(hr, "Failed to write MSI data to message buffer.");
     }
 
-    hr = BuffWriteNumber(&pbData, &cbData, pMessage->dwAllowedResults);
+    hr = BuffWriteNumber(&pbData, &cbData, pMessage->dwUIHint);
     ExitOnFailure(hr, "Failed to write UI flags.");
 
     switch (pMessage->type)
@@ -3114,11 +3120,15 @@ static int MsiExecuteMessageHandler(
         dwMessage = BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_MSI_MESSAGE;
         break;
 
+    case WIU_MSI_EXECUTE_MESSAGE_MSI_RM_FILES_IN_USE:
+        fRestartManager = TRUE;
+        __fallthrough;
     case WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE:
-        // NOTE: we do not serialize other message data here because all the "files in use" are in the data above.
+        hr = BuffWriteNumber(&pbData, &cbData, (DWORD)fRestartManager);
+        ExitOnFailure(hr, "Failed to write fRestartManager to message buffer.");
 
         // set message id
-        dwMessage = BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_FILES_IN_USE;
+        dwMessage = BURN_ELEVATION_MESSAGE_TYPE_EXECUTE_MSI_FILES_IN_USE;
         break;
 
     default:
diff --git a/src/burn/engine/embedded.cpp b/src/burn/engine/embedded.cpp
index 03898ebd..1c295d59 100644
--- a/src/burn/engine/embedded.cpp
+++ b/src/burn/engine/embedded.cpp
@@ -161,7 +161,7 @@ static HRESULT OnEmbeddedErrorMessage(
 
     message.error.wzMessage = sczMessage;
 
-    hr = BuffReadNumber(pbData, cbData, &iData, &message.dwAllowedResults);
+    hr = BuffReadNumber(pbData, cbData, &iData, &message.dwUIHint);
     ExitOnFailure(hr, "Failed to read UI hint from buffer.");
 
     *pdwResult = (DWORD)pfnMessageHandler(&message, pvContext);
@@ -185,7 +185,7 @@ static HRESULT OnEmbeddedProgress(
     GENERIC_EXECUTE_MESSAGE message = { };
 
     message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
 
     hr = BuffReadNumber(pbData, cbData, &iData, &message.progress.dwPercentage);
     ExitOnFailure(hr, "Failed to read progress from buffer.");
diff --git a/src/burn/engine/exeengine.cpp b/src/burn/engine/exeengine.cpp
index 67da3bdd..b728f599 100644
--- a/src/burn/engine/exeengine.cpp
+++ b/src/burn/engine/exeengine.cpp
@@ -533,7 +533,7 @@ extern "C" HRESULT ExeEngineExecutePackage(
         do
         {
             message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-            message.dwAllowedResults = MB_OKCANCEL;
+            message.dwUIHint = MB_OKCANCEL;
             message.progress.dwPercentage = 50;
             nResult = pfnGenericMessageHandler(&message, pvContext);
             hr = (IDOK == nResult || IDNOACTION == nResult) ? S_OK : IDCANCEL == nResult ? HRESULT_FROM_WIN32(ERROR_INSTALL_USEREXIT) : HRESULT_FROM_WIN32(ERROR_INSTALL_FAILURE);
diff --git a/src/burn/engine/msuengine.cpp b/src/burn/engine/msuengine.cpp
index 1ce2dd11..693bb64b 100644
--- a/src/burn/engine/msuengine.cpp
+++ b/src/burn/engine/msuengine.cpp
@@ -339,7 +339,7 @@ extern "C" HRESULT MsuEngineExecutePackage(
     do
     {
         message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-        message.dwAllowedResults = MB_OKCANCEL;
+        message.dwUIHint = MB_OKCANCEL;
         message.progress.dwPercentage = 50;
         nResult = pfnGenericMessageHandler(&message, pvContext);
         hr = (IDOK == nResult || IDNOACTION == nResult) ? S_OK : IDCANCEL == nResult ? HRESULT_FROM_WIN32(ERROR_INSTALL_USEREXIT) : HRESULT_FROM_WIN32(ERROR_INSTALL_FAILURE);
diff --git a/src/burn/engine/netfxchainer.cpp b/src/burn/engine/netfxchainer.cpp
index 4e7a7720..af4f03f5 100644
--- a/src/burn/engine/netfxchainer.cpp
+++ b/src/burn/engine/netfxchainer.cpp
@@ -233,8 +233,8 @@ static HRESULT OnNetFxFilesInUse(
     }
 
     // send message
-    message.type = GENERIC_EXECUTE_MESSAGE_FILES_IN_USE;
-    message.dwAllowedResults = MB_ABORTRETRYIGNORE;
+    message.type = GENERIC_EXECUTE_MESSAGE_NETFX_FILES_IN_USE;
+    message.dwUIHint = MB_ABORTRETRYIGNORE;
     message.filesInUse.cFiles = cFiles;
     message.filesInUse.rgwzFiles = (LPCWSTR*)rgwzFiles;
     dwResponse = (DWORD)pfnMessageHandler(&message, pvContext);
@@ -259,7 +259,7 @@ static HRESULT OnNetFxProgress(
 
     // send message
     message.type = GENERIC_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
     message.progress.dwPercentage = 100 * (DWORD)bProgress / BYTE_MAX;
     dwResponse = (DWORD)pfnMessageHandler(&message, pvContext);
 
@@ -283,7 +283,7 @@ static HRESULT OnNetFxError(
 
     // send message
     message.type = GENERIC_EXECUTE_MESSAGE_ERROR;
-    message.dwAllowedResults = MB_OK;
+    message.dwUIHint = MB_OK;
     message.error.dwErrorCode = hrError;
     message.error.wzMessage = NULL;
     dwResponse = (DWORD)pfnMessageHandler(&message, pvContext);
diff --git a/src/burn/engine/userexperience.cpp b/src/burn/engine/userexperience.cpp
index a6d670ea..7cc6f049 100644
--- a/src/burn/engine/userexperience.cpp
+++ b/src/burn/engine/userexperience.cpp
@@ -1494,6 +1494,7 @@ EXTERN_C BAAPI UserExperienceOnExecuteFilesInUse(
     __in_z LPCWSTR wzPackageId,
     __in DWORD cFiles,
     __in_ecount_z_opt(cFiles) LPCWSTR* rgwzFiles,
+    __in BOOTSTRAPPER_FILES_IN_USE_TYPE source,
     __inout int* pnResult
     )
 {
@@ -1506,6 +1507,7 @@ EXTERN_C BAAPI UserExperienceOnExecuteFilesInUse(
     args.cFiles = cFiles;
     args.rgwzFiles = rgwzFiles;
     args.nRecommendation = *pnResult;
+    args.source = source;
 
     results.cbSize = sizeof(results);
     results.nResult = *pnResult;
@@ -2492,13 +2494,12 @@ static int FilterResult(
     __in int nResult
     )
 {
-    DWORD dwFilteredAllowedResults = dwAllowedResults & MB_TYPEMASK;
     if (IDNOACTION == nResult || IDERROR == nResult) // do nothing and errors pass through.
     {
     }
     else
     {
-        switch (dwFilteredAllowedResults)
+        switch (dwAllowedResults)
         {
         case MB_OK:
             nResult = IDOK;
@@ -2606,7 +2607,28 @@ static int FilterResult(
             }
             break;
 
-        case WIU_MB_OKIGNORECANCELRETRY: // custom Windows Installer utility return code.
+        case BURN_MB_MSI_FILES_IN_USE:
+            // https://docs.microsoft.com/en-us/windows/win32/msi/installvalidate-action
+            if (IDRETRY == nResult || IDTRYAGAIN == nResult)
+            {
+                nResult = IDRETRY;
+            }
+            else if (IDCANCEL == nResult || IDABORT == nResult)
+            {
+                nResult = IDCANCEL;
+            }
+            else if (IDCONTINUE == nResult || IDIGNORE == nResult)
+            {
+                nResult = IDIGNORE;
+            }
+            else
+            {
+                nResult = IDNOACTION;
+            }
+            break;
+
+        case BURN_MB_MSI_RM_FILES_IN_USE:
+            // https://docs.microsoft.com/en-us/windows/win32/msi/using-restart-manager-with-an-external-ui-
             if (IDOK == nResult || IDYES == nResult)
             {
                 nResult = IDOK;
@@ -2615,11 +2637,15 @@ static int FilterResult(
             {
                 nResult = IDIGNORE;
             }
+            else if (IDNO == nResult)
+            {
+                nResult = IDNO;
+            }
             else if (IDCANCEL == nResult || IDABORT == nResult)
             {
                 nResult = IDCANCEL;
             }
-            else if (IDRETRY == nResult || IDTRYAGAIN == nResult || IDNO == nResult)
+            else if (IDRETRY == nResult || IDTRYAGAIN == nResult)
             {
                 nResult = IDRETRY;
             }
@@ -2629,13 +2655,33 @@ static int FilterResult(
             }
             break;
 
-        case MB_RETRYTRYAGAIN: // custom return code.
+        case BURN_MB_RETRYTRYAGAIN: // custom return code.
             if (IDRETRY != nResult && IDTRYAGAIN != nResult)
             {
                 nResult = IDNOACTION;
             }
             break;
 
+        case BURN_MB_NETFX_FILES_IN_USE:
+            // https://docs.microsoft.com/en-us/dotnet/framework/deployment/how-to-get-progress-from-the-dotnet-installer
+            if (IDOK == nResult || IDYES == nResult)
+            {
+                nResult = IDYES;
+            }
+            else if (IDRETRY == nResult || IDTRYAGAIN == nResult)
+            {
+                nResult = IDRETRY;
+            }
+            else if (IDCANCEL == nResult || IDABORT == nResult)
+            {
+                nResult = IDCANCEL;
+            }
+            else
+            {
+                nResult = IDNO;
+            }
+            break;
+
         default:
             AssertSz(FALSE, "Unknown allowed results.");
             break;
diff --git a/src/burn/engine/userexperience.h b/src/burn/engine/userexperience.h
index f7ac962c..75723afa 100644
--- a/src/burn/engine/userexperience.h
+++ b/src/burn/engine/userexperience.h
@@ -10,7 +10,10 @@ extern "C" {
 
 // constants
 
-const DWORD MB_RETRYTRYAGAIN = 0xF;
+const DWORD BURN_MB_RETRYTRYAGAIN = 0x10;
+const DWORD BURN_MB_MSI_FILES_IN_USE = 0x11;
+const DWORD BURN_MB_MSI_RM_FILES_IN_USE = 0x12;
+const DWORD BURN_MB_NETFX_FILES_IN_USE = 0x13;
 
 
 // structs
@@ -356,6 +359,7 @@ BAAPI UserExperienceOnExecuteFilesInUse(
     __in_z LPCWSTR wzPackageId,
     __in DWORD cFiles,
     __in_ecount_z_opt(cFiles) LPCWSTR* rgwzFiles,
+    __in BOOTSTRAPPER_FILES_IN_USE_TYPE source,
     __inout int* pnResult
     );
 BAAPI UserExperienceOnExecuteMsiMessage(
diff --git a/src/internal/SetBuildNumber/Directory.Packages.props.pp b/src/internal/SetBuildNumber/Directory.Packages.props.pp
index 4743fb2e..86f9d8cb 100644
--- a/src/internal/SetBuildNumber/Directory.Packages.props.pp
+++ b/src/internal/SetBuildNumber/Directory.Packages.props.pp
@@ -29,6 +29,7 @@
     <PackageVersion Include="WixToolset.Bal.wixext" Version="{packageversion}" />
     <PackageVersion Include="WixToolset.Dependency.wixext" Version="{packageversion}" />
     <PackageVersion Include="WixToolset.NetFx.wixext" Version="{packageversion}" />
+    <PackageVersion Include="WixToolset.UI.wixext" Version="{packageversion}" />
     <PackageVersion Include="WixToolset.Util.wixext" Version="{packageversion}" />
   </ItemGroup>
 
diff --git a/src/libs/dutil/WixToolset.DUtil/inc/wiutil.h b/src/libs/dutil/WixToolset.DUtil/inc/wiutil.h
index 9c2de209..0ddcd893 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/wiutil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/wiutil.h
@@ -9,7 +9,6 @@ extern "C" {
 // constants
 
 #define IDNOACTION 0
-#define WIU_MB_OKIGNORECANCELRETRY 0xE
 
 #define MAX_DARWIN_KEY 73
 #define MAX_DARWIN_COLUMN 255
@@ -37,6 +36,7 @@ typedef enum WIU_MSI_EXECUTE_MESSAGE_TYPE
     WIU_MSI_EXECUTE_MESSAGE_ERROR,
     WIU_MSI_EXECUTE_MESSAGE_MSI_MESSAGE,
     WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE,
+    WIU_MSI_EXECUTE_MESSAGE_MSI_RM_FILES_IN_USE,
 } WIU_MSI_EXECUTE_MESSAGE_TYPE;
 
 
@@ -45,7 +45,7 @@ typedef enum WIU_MSI_EXECUTE_MESSAGE_TYPE
 typedef struct _WIU_MSI_EXECUTE_MESSAGE
 {
     WIU_MSI_EXECUTE_MESSAGE_TYPE type;
-    DWORD dwAllowedResults;
+    DWORD dwUIHint;
 
     DWORD cData;
     LPCWSTR* rgwzData;
diff --git a/src/libs/dutil/WixToolset.DUtil/wiutil.cpp b/src/libs/dutil/WixToolset.DUtil/wiutil.cpp
index 7414ac42..da7cffe7 100644
--- a/src/libs/dutil/WixToolset.DUtil/wiutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/wiutil.cpp
@@ -113,6 +113,7 @@ static INT SendErrorMessage(
     );
 static INT SendFilesInUseMessage(
     __in WIU_MSI_EXECUTE_CONTEXT* pContext,
+    __in UINT uiFlags,
     __in_opt MSIHANDLE hRecord,
     __in BOOL fRestartManagerRequest
     );
@@ -1161,7 +1162,7 @@ Trace(REPORT_STANDARD, "MSI install[%x]: %ls", pContext->dwCurrentProgressIndex,
 
     case INSTALLMESSAGE_FILESINUSE:
     case INSTALLMESSAGE_RMFILESINUSE:
-        nResult = SendFilesInUseMessage(pContext, hRecord, INSTALLMESSAGE_RMFILESINUSE == mt);
+        nResult = SendFilesInUseMessage(pContext, uiFlags, hRecord, INSTALLMESSAGE_RMFILESINUSE == mt);
         break;
 
 /*
@@ -1401,7 +1402,7 @@ static INT SendMsiMessage(
     InitializeMessageData(hRecord, &rgsczData, &cData);
 
     message.type = WIU_MSI_EXECUTE_MESSAGE_MSI_MESSAGE;
-    message.dwAllowedResults = uiFlags;
+    message.dwUIHint = uiFlags;
     message.cData = cData;
     message.rgwzData = (LPCWSTR*)rgsczData;
     message.msiMessage.mt = mt;
@@ -1445,7 +1446,7 @@ static INT SendErrorMessage(
     InitializeMessageData(hRecord, &rgsczData, &cData);
 
     message.type = WIU_MSI_EXECUTE_MESSAGE_ERROR;
-    message.dwAllowedResults = uiFlags;
+    message.dwUIHint = uiFlags;
     message.nResultRecommendation = nResult;
     message.cData = cData;
     message.rgwzData = (LPCWSTR*)rgsczData;
@@ -1459,8 +1460,9 @@ static INT SendErrorMessage(
 
 static INT SendFilesInUseMessage(
     __in WIU_MSI_EXECUTE_CONTEXT* pContext,
+    __in UINT uiFlags,
     __in_opt MSIHANDLE hRecord,
-    __in BOOL /*fRestartManagerRequest*/
+    __in BOOL fRestartManagerRequest
     )
 {
     INT nResult = IDNOACTION;
@@ -1470,8 +1472,8 @@ static INT SendFilesInUseMessage(
 
     InitializeMessageData(hRecord, &rgsczData, &cData);
 
-    message.type = WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE;
-    message.dwAllowedResults = WIU_MB_OKIGNORECANCELRETRY;
+    message.type = fRestartManagerRequest ? WIU_MSI_EXECUTE_MESSAGE_MSI_RM_FILES_IN_USE : WIU_MSI_EXECUTE_MESSAGE_MSI_FILES_IN_USE;
+    message.dwUIHint = uiFlags;
     message.cData = cData;
     message.rgwzData = (LPCWSTR*)rgsczData;
     message.msiFilesInUse.cFiles = message.cData;       // point the files in use information to the message record information.
@@ -1527,7 +1529,7 @@ static INT SendProgressUpdate(
 #endif
 
     message.type = WIU_MSI_EXECUTE_MESSAGE_PROGRESS;
-    message.dwAllowedResults = MB_OKCANCEL;
+    message.dwUIHint = MB_OKCANCEL;
     message.progress.dwPercentage = dwPercentage;
     nResult = pContext->pfnMessageHandler(&message, pContext->pvContext);
 
diff --git a/src/test/burn/TestBA/TestBA.cs b/src/test/burn/TestBA/TestBA.cs
index 5c70253d..5ef26253 100644
--- a/src/test/burn/TestBA/TestBA.cs
+++ b/src/test/burn/TestBA/TestBA.cs
@@ -399,7 +399,7 @@ namespace WixToolset.Test.BA
 
         protected override void OnExecuteFilesInUse(ExecuteFilesInUseEventArgs args)
         {
-            this.Log("OnExecuteFilesInUse() - package: {0}, retries remaining: {1}, data: {2}", args.PackageId, this.retryExecuteFilesInUse, String.Join(", ", args.Files.ToArray()));
+            this.Log("OnExecuteFilesInUse() - package: {0}, source: {1}, retries remaining: {2}, data: {3}", args.PackageId, args.Source, this.retryExecuteFilesInUse, String.Join(", ", args.Files.ToArray()));
 
             if (this.retryExecuteFilesInUse > 0)
             {
diff --git a/src/test/burn/TestData/FilesInUseTests/BundleA/BundleA.wixproj b/src/test/burn/TestData/FilesInUseTests/BundleA/BundleA.wixproj
new file mode 100644
index 00000000..c71410c2
--- /dev/null
+++ b/src/test/burn/TestData/FilesInUseTests/BundleA/BundleA.wixproj
@@ -0,0 +1,18 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <OutputType>Bundle</OutputType>
+    <UpgradeCode>{6A348108-8ACE-4D13-A352-D8F76785BFE4}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Bundle.wxs" Link="Bundle.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\PackageA\PackageA.wixproj" />
+    <ProjectReference Include="..\..\TestBA\TestBAWixlib\testbawixlib.wixproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.Bal.wixext" />
+    <PackageReference Include="WixToolset.NetFx.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/FilesInUseTests/BundleA/BundleA.wxs b/src/test/burn/TestData/FilesInUseTests/BundleA/BundleA.wxs
new file mode 100644
index 00000000..bd164a29
--- /dev/null
+++ b/src/test/burn/TestData/FilesInUseTests/BundleA/BundleA.wxs
@@ -0,0 +1,10 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">
+  <Fragment>
+    <PackageGroup Id="BundlePackages">
+      <MsiPackage Id="PackageA" SourceFile="$(var.PackageA.TargetPath)" />
+    </PackageGroup>
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/FilesInUseTests/PackageA/PackageA.wixproj b/src/test/burn/TestData/FilesInUseTests/PackageA/PackageA.wixproj
new file mode 100644
index 00000000..57825f7b
--- /dev/null
+++ b/src/test/burn/TestData/FilesInUseTests/PackageA/PackageA.wixproj
@@ -0,0 +1,13 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+<Project Sdk="WixToolset.Sdk">
+  <PropertyGroup>
+    <ProductComponentsRef>true</ProductComponentsRef>
+    <UpgradeCode>{C94C8FC9-1347-44CE-B1FB-0A6196928921}</UpgradeCode>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Templates\Package.wxs" Link="Package.wxs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="WixToolset.UI.wixext" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/test/burn/TestData/FilesInUseTests/PackageA/PackageA.wxs b/src/test/burn/TestData/FilesInUseTests/PackageA/PackageA.wxs
new file mode 100644
index 00000000..a96c2a11
--- /dev/null
+++ b/src/test/burn/TestData/FilesInUseTests/PackageA/PackageA.wxs
@@ -0,0 +1,10 @@
+<!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information. -->
+
+<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">
+  <Fragment>
+    <ComponentGroup Id="ProductComponents" />
+
+    <UIRef Id="WixUI_Minimal" />
+    <WixVariable Id="WixUILicenseRtf" Value="license.txt" />
+  </Fragment>
+</Wix>
diff --git a/src/test/burn/TestData/FilesInUseTests/PackageA/license.txt b/src/test/burn/TestData/FilesInUseTests/PackageA/license.txt
new file mode 100644
index 00000000..2e65efe2
--- /dev/null
+++ b/src/test/burn/TestData/FilesInUseTests/PackageA/license.txt
@@ -0,0 +1 @@
+a
\ No newline at end of file
diff --git a/src/test/burn/WixToolsetTest.BurnE2E/FilesInUseTests.cs b/src/test/burn/WixToolsetTest.BurnE2E/FilesInUseTests.cs
new file mode 100644
index 00000000..6ad68d22
--- /dev/null
+++ b/src/test/burn/WixToolsetTest.BurnE2E/FilesInUseTests.cs
@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolsetTest.BurnE2E
+{
+    using System.IO;
+    using WixTestTools;
+    using Xunit;
+    using Xunit.Abstractions;
+
+    public class FilesInUseTests : BurnE2ETests
+    {
+        public FilesInUseTests(ITestOutputHelper testOutputHelper) : base(testOutputHelper) { }
+
+        [Fact]
+        public void CanCancelInstallAfterRetryingLockedFile()
+        {
+            var packageA = this.CreatePackageInstaller("PackageA");
+            var bundleA = this.CreateBundleInstaller("BundleA");
+            var testBAController = this.CreateTestBAController();
+
+            testBAController.SetPackageRetryExecuteFilesInUse("PackageA", 1);
+
+            packageA.VerifyInstalled(false);
+
+            // Lock the file that will be installed.
+            string targetInstallFile = packageA.GetInstalledFilePath("Package.wxs");
+            Directory.CreateDirectory(Path.GetDirectoryName(targetInstallFile));
+            using (FileStream lockTargetFile = new FileStream(targetInstallFile, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.None, 4096, FileOptions.DeleteOnClose))
+            {
+                bundleA.Install(expectedExitCode: (int)MSIExec.MSIExecReturnCode.ERROR_INSTALL_USEREXIT);
+            }
+
+            bundleA.VerifyUnregisteredAndRemovedFromPackageCache();
+
+            packageA.VerifyInstalled(false);
+        }
+    }
+}
diff --git a/src/test/burn/WixToolsetTest.BurnE2E/TestBAController.cs b/src/test/burn/WixToolsetTest.BurnE2E/TestBAController.cs
index 6e4fe6c6..d2e8a1ca 100644
--- a/src/test/burn/WixToolsetTest.BurnE2E/TestBAController.cs
+++ b/src/test/burn/WixToolsetTest.BurnE2E/TestBAController.cs
@@ -118,6 +118,16 @@ namespace WixToolsetTest.BurnE2E
         }
 
         /// <summary>
+        /// Retries the files in use one or more times before canceling.
+        /// </summary>
+        /// <param name="packageId">Package identity.</param>
+        /// <param name="cancelPoint">Sets or removes the retry count on a package's file in use message.</param>
+        public void SetPackageRetryExecuteFilesInUse(string packageId, int? retryCount)
+        {
+            this.SetPackageState(packageId, "RetryExecuteFilesInUse", retryCount.HasValue ? retryCount.ToString() : null);
+        }
+
+        /// <summary>
         /// Sets the requested state for a package that the TestBA will return to the engine during plan.
         /// </summary>
         /// <param name="packageId">Package identity.</param>