@popey, thanks for this info.
Just to be clear for anyone else on this forum. @popey post above is not related to any snap package, but Calibre package from official Ubuntu apt repository.
For Calibre Ubuntu 20.04 official apt repository there is currently opened a bug report and 11 duplicates, so many users are affected. Bug report is at:
The beauty of Calibre is, it is written in Python code, so very simple to fix this problem. In bug report someone prepared the Python code patch (one line of code actually is only needed) and another users created bash script to apply the fix on Ubuntu 20.04. I tested this solution and problem is fixed on my computer. But I hope the proper official fix is released for non-nerd users.
It looks to me there are several problems:
- Calibre 4.99 shipped with Ubuntu 20.04 was Calibre Python3’s test bed version. This was never meant to be official version. When proper Calibre’s Pyhon3 version was released upstream it was named with version 5, but it was never imported into Ubuntu 20.04.
- Ubuntu 20.04 LTS version ships beta type code.
- In this case it is lack of control that upstream has changed something and didn’t fix it downstream.
- One Python3 package updated in Ubuntu 20.04 and Calibre was broken.
- Just guessing (speculation), the package maintainer of Calibre on Ubuntu 20.04 does not use Calibre day to day, because if he/she is, I would expect to fix this one line problem and release update very quickly.
- Fix is known for few days and update was still not prepared to be shipped to Ubuntu 20.04. Lack of maintenance etc.
In general having centralized software like installing from apt can have drastic consequences if something changes. That is the reason I requested Calibre snap package, so I can have a program that is independent of host operating system changes.