Installer created via Inno Setup, can't close applications during installation on Windows 10

Question

I have created an installer for my application using Inno Setup. For a while everything works fine but recently installer failing to close explorer.exe (Windows Explorer) on Windows 10 during installation. Installer needs to restart it to replace existing context menu handler with new, but the more strange thing is that same installer works fine on Windows 8 and 8.1. Adding restartreplace flag does not helps.

I also noticed that the installer can't close currently running application (old one which needs to be updated) and like the previous problem the application can be closed in Windows 8 or 8.1 with same installer.

Here is the log from Inno Setup installer:

[11:22:34.819]   Setup application started
[11:22:34.983]   Setup version: Inno Setup version 5.5.9 (a)
[11:22:34.984]   Original Setup EXE: ***
[11:22:34.984]   Setup command line: /SL5="$C0928,15589089,85504,***" /DEBUGWND=$30464 
[11:22:34.985]   Windows version: 10.0.14393  (NT platform: Yes)
[11:22:34.985]   64-bit Windows: Yes
[11:22:34.985]   Processor architecture: x64
[11:22:34.985]   User privileges: Administrative
[11:22:34.987]   64-bit install mode: Yes
[11:22:34.991]   Created temporary directory: C:\Users\Azat\AppData\Local\Temp\is-M4710.tmp
[11:22:37.584]   RestartManager found an application using one of our files: Windows Explorer
[11:22:37.585]   Can use RestartManager to avoid reboot? Yes (0)
[11:22:39.780]   Starting the installation process.
[11:22:39.789]   Shutting down applications using our files.
[11:23:09.944]   Some applications could not be shut down.
[11:23:09.945]   Message box (Abort/Retry/Ignore):
   Setup was unable to automatically close all applications. It is recommended that you close all applications using files that need to be updated by Setup before continuing.

   Click Retry to try again, Ignore to proceed anyway, or Abort to cancel installation.
[11:25:30.543]   User chose Abort.
[11:25:30.544]   User canceled the installation process.
[11:25:30.545]   Rolling back changes.
[11:25:30.547]   Starting the uninstallation process.
[11:25:30.548]   Uninstallation process succeeded.
[11:25:32.049]   Deinitializing Setup.
[11:25:32.071]   Setup exit code: 5

Answer 1

I do not know why the installer is failing to close the applications.

But you can try the force option to work it around:

CloseApplications=force

Answer 2

I had a case that CloseApplications=force didn't help, and the only solution was to manually kill the running app.

I eventually used something like this:

[Files]
Source: "My Service 1.exe"; DestDir: "{app}"; Flags: ignoreversion; BeforeInstall: TaskKill('My Service 1.exe')

[Code]
procedure TaskKill(fileName: String);
var
    resultCode: Integer;
begin
    Exec(ExpandConstant('taskkill.exe'), '/f /im ' + '"' + fileName + '"', '', SW_HIDE, ewWaitUntilTerminated, resultCode);
end;

Source - https://stackoverflow.com/a/33776406/426315