flask-apscheduler | Adds APScheduler support to Flask

You're using old mysqlclient 1.3.12 with new MySQL 8. Either you need to downgrade MySQL to version 5.6. Or you need to use later mysqlclient.

The incompatibility was fixed in commit a2ebbd2 on Dec 21, 2017 so you need a later version of mysqlclient.

mysqlclient 1.3.13 was released on Jun 27, 2018. Try it or any later version.

1. self.logs is not a collection of logs, but a reference to Logs as a relationship. You actually need to fetch the count first;
2. It's bad practice to count() when you actually just need to know if any log exists(). If we were cooking dinner and I asked if there was still any rice, I wouldn't expect you to count the individual grains of rice, but to just check if the pot was empty;
3. If no match exists, .first() returns None. Use it to your advantage:

Solved. The issue was that I have 2 flasks installed on my computer:

• first one is global
• second one is for my venv only

The flask run was executing the global one (because in Path environment variable there was only path to this one), but APScheduler is installed within my venv. I deleted the global flask and changed the Path variable to my venv. I don't know, if this is a proper way to solve it, but now it works.