User already has more than ‘max_user_connections’ active connections
The message is pretty self explanatory: there are too many connections to the database active at the same time.
There are two explanations I can think of:
The website gets a lot of traffic which means many scripts are executing and interacting with the database.
The software opens many database connections at the same time for no reason (I don’t think it’s possible to execute multiple database queries at the same time), so this is a bug in the software.