1- Migrate Assignments from 2.2.1 to 2.3.2
2- Go to grades and in Grader report, turn editing on and add a grade manually.
3- Click on the Edit grade
4- Uncheck Overriden and save changes

The page will stay unresponsive and then a white page with the following error appears:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 76 bytes) in /app/apache2/htdocs/moodle/lib/dml/mysqli_native_moodle_database.php on line 944

And the grade doesn't return to the previous state. (It stays on the overriden grade)

This doesn't happen with the newly created assignments but only with the migrated ones.