Deployment issue, System.TypeLoadException

Deployment issue, System.TypeLoadException

We recently updated our web application from dotConnect for MySQL 8.17 to 9.0.0 (with EF5). Everything works fine on dev machines but not when deployed to the web server (Windows Server 2012):


System.Data.EntityCommandCompilationException: An error occurred while preparing the command definition. See the inner exception for details. ---> System.TypeLoadException: Inheritance security rules violated by type: 'Devart.Common.Entity.ei'. Derived types must either match the security accessibility of the base type or be less accessible.

Any clues to how to fix it?