How to upgrade MySQL 5.1 to MySQL 5.7 in Plesk Obsidian for Windows?
Starting from Plesk Obsidian the MariaDB of 10.x version is used as a default database server.
Thus the only way to upgrade MySQL 5.1 here is to convert it to MariaDB 10.6 with the following steps:
Go to Tools & Settings > Updates > Add/Remove Components > MySQL Server.
Select MariaDB 10.6 server.
Scroll down and press the Continue button.