I agree it's not a duplicate, and I don't know why ~juanjo-benages marked it as such.
The PyCapsule error indicates a faulty build (possibly needs to be rebuilt for pyqt). The AttributeError: 'NoneType' object has no attribute 'cancel' error is due to changes in python 3.8 between 3.8.2 and 3.8.3. Both are bugs, both prevent running calibre, but they're not the SAME bug and they don't apply to the same builds. Apparently, some people merely saw "cannot start calibre" and lumped them all together. ** This bug is no longer a duplicate of bug 1898904 Calibre crashes at startup with AttributeError: 'NoneType' object has no attribute 'cancel' -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1884525 Title: Cannot start calibre To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/calibre/+bug/1884525/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
