by Emma Richardson.
You can import the courses straight from 2.9 to 3.3 using backup and restore. The issues you mentioned should not come across - that sounds more like server issues. However, if you run 3.3 on the same server, you might still have issues. You will need to check your php settings with the new site to make sure everything is functional.
1. Grades not showing up - if only some grades are showing in the grader report, this is most likely the max_input_vars setting in php.ini being too low.
2. If outbound emails are not going out, you need to look at your email settings in moodle and if they are just set to use the phpmailer on the server, then you need to check that it is functional and present.
3. The back up and restore not working sounds like maybe a permissions issue or a corrupted folder/file from the migration.