uninstaller doesn't delete all installed files - install4j

Question

We have a strange problem during our uninstall process.
After the uninstaller finishes, the user custom sources and some parts of the jre are still present on the system. In the uninstaller.log it states the postponed deletion of some of these files, but not all of them.
Has someone an idea why the deletion is postponed and why they are not deleted at all?
Additionally that doesnt happen on all systems, but is reproducable per system. For example on my developer machine everything works fine, but on a fresh vm the problem occurs.
[INFO] com.install4j.runtime.beans.actions.UninstallFilesAction [ID 29]: Execute action
executing auto uninstall
postponing deletion of C:\Program Files (x86)\mytool\jre\lib\rt.jar
postponing deletion of C:\Program Files (x86)\mytool\.install4j\user.jar
postponing deletion of C:\Program Files (x86)\mytool\.install4j\i4jruntime.jar
postponing deletion of C:\Program Files (x86)\mytool\jre\lib\resources.jar
postponing deletion of C:\Program Files (x86)\mytool\jre\lib\jsse.jar
postponing deletion of C:\Program Files (x86)\mytool\jre\lib\charsets.jar
postponing deletion of C:\Program Files (x86)\mytool\jre\lib\jce.jar
postponing deletion of C:\Program Files (x86)\mytool\jre\lib\jfr.jar
postponing deletion of C:\Program Files (x86)\mytool\.install4j\user\myaction.jar
Execute action successful after 717 ms
my first guess was that it has something to do with the user action. but this is part of the automatic updater which is not executed at all.
edit:
after adding an action "Check for running processes" it is still the same behaviour.
[INFO] com.install4j.runtime.beans.actions.misc.CheckRunningProcessesAction [ID 738]: Execute action
Property additionalExecutables: null
Property closeStrategy: Allow soft close
Property message: install4j hat entdeckt, dass mytool zur Zeit ausgeführt wird.
Bitte schließen Sie jetzt die folgenden Instanzen, und klicken Sie auf "Wiederholen", um fortzufahren, oder auf "Abbrechen", um zu beenden.
Property timeOut: 5000
Property allowIgnore: false
Property includeLaunchers: true
Property rollbackSupported: true
Execute action successful after 0 ms
My assumption from this log message is, there were no running processes, as the action is completed after 0 seconds?

Answer 1

This means that a launcher that is using the bundled JRE is still running. Some files in the JRE are locked in that case and they cannot be deleted.
Use a "Check for running processes" action in the uninstaller to shut down all launchers before the "Uninstall files" action is executed.