Migration to a Plesk server fails with the warnings like below:
Login of FTP user '2jdoe' does not conform to Plesk rules. It was changed to 'a2jdoe'
Login of FTP user '[email protected]' does not conform to Plesk rules. It was changed to 'jdoe_example.com'.
The username does not conform to Plesk rules.
In Plesk usernames can contain a lowercase alphanumeric, dash, and underscore symbols. The username should start with a lowercase alphabetic character and should be between 1 and 16 characters in length.
This warning can be safely ignored.
Plesk Migrator automatically substitutes the name that doesn't conform to Plesk rules with the suitable one and provides this new name in the warning message.