To resolve, I had to open NP++ with only a blank document (as soon as there is any text it crashes) and uninstall “Task List”. To be able to do this, you may have to delete your session file, “…\AppData\Roaming\Notepad++\session.xml”

Any files you had opened in your session will be in “…\AppData\Roaming\Notepad++\backup” so you shouldn’t lose anything.

Hope this helps.

Please note that -noplugin does not equal -noPlugin. Command line options are case sensitive.

I pointed this out HERE where OP opened an issue.

Because I copied all of <program folder>\plugins to c:\<user>\appdata\roaming\notepad++\plugins

Wrong direction. The <program folder>\plugins\ is the right hierarchy for plugin DLLs. and each plugin needs its own eponymous folder.

But after starting NP++, there were no plugins. I searched for an entry anywhere for a path that points to a plugins folder, but I found nothing. :(

That’s because it’s hardcoded relative to notepad++.exe.

I started NP++ 8.3.1 now with the correct parameters “-noplugin -nosession” but it only started for a second and then closed again by itself. :(

Please note that -noplugin does not equal -noPlugin. Command line options are case sensitive.

The command line option you provided does nothing, and thus Notepad++ was still opening with all plugins active – and thus still crashing.

For future reference, plugins haven’t been intentionally installed in the ...\AppData\Roaming\Notepad++\plugins folder since about 2019 (v7.6.3 was the first stable release after the First Great Plugins Migration – the timestamp of most of your plugins from that folder are from 2015, but a few were from 2020, which surprises me that anything put DLLs there in 2020). Plugins Admin does not install plugin DLLs there. I would recommend not keeping any plugins there; I didn’t realize that it even still worked to have DLLs there (maybe it doesn’t; you don’t say whether any of those worked prior to your v8.3.x problems). I would recommend deleting all the DLL from the AppData hierarchy.

Because I copied all of <program folder>\plugins to c:\<user>\appdata\roaming\notepad++\plugins

But after starting NP++, there were no plugins. I searched for an entry anywhere for a path that points to a plugins folder, but I found nothing. :(

Now, 8.3.1 won’t start as I described above. :(

It seems part of the plugins are inside the program folder and part in the user folder.

I guess I’ve to find a way to clean all up.

nppAutoDetectIndent.dll is an internal DLL

No it isn’t

I would have to compile the whole sourcecode of NP++ incl. the DLLs.

Any idea what causes the problem?

Yes, breaking changings in the API that plugins will need to recompile against. Remove that plugin, launch the new N++ 8.3 and use Plugin Admin to reinstall the latest version. For more info, see here.

Cheers.