We are using Install4j v6.16.
In our uninstaller process we define "Delete files or directories" action to the installation directory by: ${installer:sys.installationDir} with the recursive option.
After the process is getting finish the .install4j directory (which contains some jars files and 1 dll file) and the uninstall.exe file won't be deleted.
If some of these files weren't be able to be deleted, the uninstaller process should have throw an error, isn't it?
On Windows, it's not possible to delete a file that is in use, so the uninstaller does this with a temporary executable in the %TEMP% directory.
The "Delete files and directories" action does not throw an error if a file cannot be deleted, it writes file paths that cannot be deleted to the log file of the uninstaller in the %TEMP% directory.
Use the "Delete files and directories" action only for specific files that are created by your application in addition to the installed files, the runtime files will be deleted automatically.
