Unsafe Files

As a convenience to new users who are unfamiliar with which files they should and should not distribute, the Inno Setup compiler will display an error message if one attempts to install certain "unsafe" files using the [Files] section. These files are listed below.

(Note: It is possible to disable the error message by using a certain flag on the [Files] section entry, but this is NOT recommended.)

Any DLL file from own Windows System directory

You should not deploy any DLLs out of your own Windows System directory to {sys} because most of them are tailored for your own specific version of Windows, and will not work when installed on other versions. Often times a user's system will be rendered unbootable if you install a DLL from a different version of Windows. Another reason why it's a bad idea is that when you install programs on your computer, the DLLs may be replaced with different/incompatible versions without your knowledge. This could lead to unexpected and difficult-to-trace problems on users' systems when you build new installations.

Instead of deploying the DLLs from your Windows System directory, you should find versions that are specifically deemed "redistributable". Redistributable DLLs typically work on more than one version of Windows. To find redistributable versions of the Visual Basic and Visual C++ run-time DLLs, see the Inno Setup FAQ.

If you have a DLL residing in the Windows System directory that you are absolutely sure is redistributable, copy it to your script's source directory and deploy it from there instead.


These are all core components of Windows and must never be deployed with an installation. Users may only get new versions of these DLLs by installing a new version of Windows or a service pack or hotfix for Windows.


If DestDir is set to a location other than {sys} and the regserver or regtypelib flag is used, then the above files will be considered "unsafe". These files must never be deployed to and registered in a directory other than {sys} because doing so can potentially cause all programs on the system to use them in favor of the files in {sys}. Problems would result if your copies of the files are older than the ones in {sys}. Also, if your copies of the files were removed, other applications would break.


Microsoft does not allow separate redistribution of COMCTL32.DLL (and for good reason - the file differs between platforms), so you should never place COMCTL32.DLL in a script's [Files] section. You can however direct your users to download the COMCTL32 update from Microsoft [external link], or distribute the COMCTL32 update along with your program.


These are core components of Internet Explorer and are also used by Windows Explorer. Replacing them may prevent Explorer from starting. If your application depends on these DLLs, or a recent version of them, then your users will need to install a recent version of Internet Explorer to get them.


This file is part of the Microsoft .NET Framework. You cannot safely install or update the .NET Framework by including this file with your installation. Call or direct your users to dotnetfx.exe instead.