Missing method on MYSQL authentication

Recently my register page has stopped working, login and other mysql functions still seem to work perfectly fine, but when I try to register I am running into this error.

An unhandled exception has occurred while executing the request.
System.MissingMethodException: Method not found: 'System.Threading.Tasks.Task`1<MySql.Data.MySqlClient.MySqlTransaction> MySql.Data.MySqlClient.MySqlConnection.BeginTransactionAsync(System.Data.IsolationLevel, System.Threading.CancellationToken)'.

Would you have any idea why this error might happen?

Ok so I am not sure this is a perfect fix, but elsewhere in the project I added this

It seems the error happened after that...
To fix it I added:
using MySql.Data.MySqlClient;
To the ApplicationIdentityDbContext.cs file

As for why I had to add that, I am using Manticore on a remote server, and thought this would be the most effective way to communicate with it.

We haven't seen this error. If this started happening recently you can try reverting to an older version to see if it would help. The Radzen user registration code hasn't changed for a long time.