I want to share my experience with hassio and the “supervisor blank” issue. In my case is happened about every 4 hours, and also addons in the interface were not responding (as an example also “file editor” on sidebar showed a blank page).
I am running hassio on Raspberry 4 with 4MB and up-to-date software as today. I also have external Crucial 120GB BX500 SSD drive (no way to make it work well on USB3 ports, many low level block errors on console - its fine on the USB2 port).
After configuring 100 entities, automations, several integrations, addons, I began to have the issue regularily after about 4 hour from boot: supervisor blank, many things not working (for example restful commands). I dont want to go into details.
I issued a “ha core rebuild” and ha host restart" and every time all restarted ok.
After trying to read lots of posts in the forum, unable to find a solution, I began to remove blocks of entities, integrations, and addons, removing them step by step and verifying stability at every step, issuing a core rebuild and a restart.
After several tries (problem arising regularily after about 4 hours), I finally deactivated GOOGLE CAST integration and KODI LibreELEC integration: everything resumed flawlessly. Finally some fresh air !! I was about to give no more time to hassio.
At this point I reconfigured all entities, addons and integrations, all was ok (still working well after 10 days).
I dont need chromecast and kodi integrations, they were installed automatically, so I will let them DISABLED.
Just to identify precisely the problem, I have now reactivated the KODI integration, we’ll see if the system breaks again after some hours.