Web control panel login issue was the first step. I couldn't log in. Then it sais:
OMV\Exception: Failed to read file '/var/cache/openmediavault/cache.omv\controlpanel\login_js.json' (size=0). in /usr/share/php/openmediavault/json/file.inc:207
#0 /usr/share/php/openmediavault/json/file.inc(223): OMV\Json\File->getContents()
#1 /usr/share/php/openmediavault/controlpanel/controlpanelabstract.inc(173): OMV\Json\File->read()
#2 /var/www/openmediavault/index.php(46): OMV\ControlPanel\ControlPanelAbstract->render()
Now if I run "df -h /" I get 100% used. Why? It was working yesterday! It was working for more than 5 days!