Crash in upgrade to 5.35.1 on task core-issue#365 - Add created_date to civicrm_action_schedule
Of course

you ran this on a development copy of the site first, so you're not panicking, right?
you took a backup before your production upgrade, and can roll back to that?
you wished you had?

If you can, revert your database to a pre-upgrade backup
Then run this SQL on the CiviCRM database: OPTIMIZE TABLE civicrm_action_schedule;
Then repeat the upgrade.
If you didn't have a backup
Then run this SQL on the CiviCRM database: OPTIMIZE TABLE civicrm_action_schedule;
Then try to resume the upgrade procedure. If you're  on the command line you can use cv upgrade:db which will probably suggest you run cv upgrade:db --retry.
Hopefully it runs through clean for you now.