Comment 1 for bug 1786224

In this changelog [0] the API v12.3 was implemented in python3-sip v4.19.5.

How do you have installed python3-sip ?

The problem of the versions conflict of the API version is common and generally solved by reinstalling python3-sip [1]

[0] http://changelogs.ubuntu.com/changelogs/pool/universe/s/sip4/sip4_4.19.7+dfsg-1/changelog
[1] https://stackoverflow.com/questions/22589497/pyqt5-sip-api-10-level-error-api-11-required