I am not aware of what causes this issue. Maybe it's related to repositories or something which gets a reset with the workaround I follow. There might be a very easy solution to rectify it but this is what I use until an official fix or a better solution is provided by the experienced guys here:
WordOps has a beta version which isn't updated for months. I use
wo update --beta command to fix the wo maintenance issue.
If you run
wo update --beta command on Ubuntu 20.04, you will simply get a message that WordOps Beta supports only Ubuntu 16.04 and 18.04. After this message, I simply run the
wo maintenance and it just works again.
Ubuntu 18.04 or Ubuntu 16.04
If you run
wo update --beta command on the older versions of Ubuntu, the WordOps will be degraded to the Older Beta Version and then you should run the command
wo update to get back to the latest version of WordOps. Voilla, you should be able to use
wo mantenance command again.
I use the same workaround when
wo stack installation fails for any particular package such as Redis, PHP-FPM etc. @rgilman I never used
Debian so I won't be able to advise but still you may try the same solution and see if it fixes the problem.