Was glad to hear that version 9.4.0 finally doesn't need the Joomla Backward Compatibility plugin anymore.
After updating Acymailing to version 9.4.0 I switched it off and #boom... site down and not accessible anymore. I needed to go into my database to enable the backward compatibility plugin again.
I opened an ssh shell to my server and searched for the incompatible jplugin class and it turns out that after upgrading to 9.4.0 the plugins where NOT upgraded causing the site outage.
On one site I have downgraded to 9.3.1 (which failed), installed 9.4.0 agian (which gave an error) and repeated that 3 or 4 times and then i saw on that site that the plugins where indeed also upgraded to version 9.4.0.
On other sites I am not that lucky: no way the plugins are upgraded.
How can I 'force' the upgrade to not only the component but also to the plugin that come with acymailing?