I guess, this is caused by my own fault:
I have removed a plugin from another thread ([Sensors] OMV-Sensors in OMV 4.1.x) to try to get it to a newer version.
After deletion of this, the OMV startscreen (dashboard) is no longer accessible. Only the OMV logo is displayed on top of the browser.
I guess this is because a reference to a graph from the removed plugin is still somewhere in the system and now it cannot find the plugin, which is causing exceptions.
Can you please let me know, where to see the configuration of the dashboard page on a file system level?
Everything else is working fine, so that is the only issue I can see so far.