In my installer (Basic MSI project) I have a file to be installed under following location - C:\Program Files\Common Files\AppFolder\AppFolder2\17\drivers\test.dll  I wanted this file to exist only during the installer process.  Post install I want to delete the file.  So I have added a CustomAction to delete the file however I keep getting  "The system cannot open the file".  My customAction function: function DeleteDLLFile(hMSI) STRING szCommonFilesDir, szMBSWVersionDir; NUMBER nSize,nSize2,nResult; STRING szFilePath; begin // Get the installed path location MsiGetProperty(hMSI, "TSSCOMMONFILESFOLDER", szCommonFilesDir, nSize); SprintfMsiLog("In DeleteDLLFile - TSSCOMMONFILESFOLDER - " + szCommonFilesDir); MsiGetProperty(hMSI, "MBSWVersion", szMBSWVersionDir, nSize2); SprintfMsiLog("In DeleteDLLFile - MBSWVersion - " + szMBSWVersionDir); szFilePath = szCommonFilesDir ^ "AppFolder2" ^ szMBSWVersionDir ^ "drivers" ^ "test.dll"; SprintfMsiLog("In DeleteDLLFile - Before path changes '%s'", szFilePath); // replace backslashes with double backslashes StrReplace (szFilePath, "\\" , "\\\\", 0); SprintfMsiLog("In DeleteDLLFile - After path changes '%s'", szFilePath); SprintfMsiLog("In DeleteDLLFile - Before calling DeleteFile '%s'", szFilePath); nResult = DeleteFile ("'" + szFilePath + "'"); if (nResult < 0) then SprintfMsiLog ("Failed to delete '%s' reason '%s'", ERRORFILENAME, FormatMessage(nResult)); else SprintfMsiLog ("File '%s' was deleted.", szFilePath); endif; SprintfMsiLog("In DeleteDLLFile - Finished calling DeleteFile() with file path '%s'", szFilePath); end; Installshiled log: InstallShield 15:03:57: Running InstallScript function f5 InstallShield 15:03:57: Opening stream of file C:\Windows\Installer\MSID294.tmp InstallShield 15:03:57: Extracting support file IsConfig.ini to C:\Users\~1\AppData\Local\Temp\{E9478B8B-CC39-4AAF-9831-081E21D3C032}\IsConfig.ini InstallShield 15:03:57: Extracted isconfig.ini to C:\Users\~1\AppData\Local\Temp\{E9478B8B-CC39-4AAF-9831-081E21D3C032}\IsConfig.ini InstallShield 15:03:57: Got '{DBB5C17E-0AC3-4D0C-9645-D5CBD108697C}' for TempPathGuid from isconfig.ini InstallShield 15:03:57: Attempting to use temp path 'C:\Users\~1\AppData\Local\Temp\{DBB5C17E-0AC3-4D0C-9645-D5CBD108697C}' InstallShield 15:03:57: Using new temp path InstallShield 15:03:57: Cleaning up temp file C:\Users\~1\AppData\Local\Temp\{E9478B8B-CC39-4AAF-9831-081E21D3C032}\IsConfig.ini InstallShield 15:03:57: Using temp folder C:\Users\~1\AppData\Local\Temp\{DBB5C17E-0AC3-4D0C-9645-D5CBD108697C} InstallShield 15:03:57: Installing engine... InstallShield 15:03:57: Using product language 1033 InstallShield 15:03:57: Detected X64 OS InstallShield 15:03:57: Skipping optional support file _isuser_0x0409.dll InstallShield 15:03:57: Setting script cmdline... InstallShield 15:03:57: ProductCode is {9A1E98E9-9819-4F06-8DBB-F5FDC0F8A4EA} InstallShield 15:03:57: Initializing Engine InstallShield 15:03:57: Done Initializing... InstallShield 15:03:57: Registering Msi Server... InstallShield 15:03:57: Invoking script function DeleteDLLFile 1: In DeleteDLLFile - TSSCOMMONFILESFOLDER - C:\Program Files\Common Files\AppFolder\ 1: In DeleteDLLFile - MBSWVersion - 17 1: In DeleteDLLFile - Before path changes 'C:\Program Files\Common Files\AppFolder\AppFolder2\17\drivers\test.dll' 1: In DeleteDLLFile - After path changes 'C:\\Program Files\\Common Files\\AppFolder\\AppFolder2\\17\\drivers\\test.dll' 1: In DeleteDLLFile - Before calling DeleteFile 'C:\\Program Files\\Common Files\\AppFolder\\AppFolder2\\17\\drivers\\test.dll' 1: Failed to delete '' reason 'The system cannot open the file. ' 1: In DeleteDLLFile - Finished calling DeleteFile() with file path 'C:\\Program Files\\Common Files\\AppFolder\\AppFolder2\\17\\drivers\\test.dll' InstallShield 15:03:57: Returning script function result InstallShield 15:03:57: CallScriptFunctionFromMsiCA() ends, result 0x0 Action ended 15:03:57: DeleteDLLFile. Return value 1.     I am new to installshield, please can someone advise on this   ... View more