This issue often occurs when there is a mismatch between different versions of libraries being used in your application.
After upgrading the SAML module, try cleaning and rebuilding your Mendix application to ensure that the new changes are correctly integrated.
Review the documentation of the SAML module you upgraded to. It might provide specific instructions or requirements for the upgrade process.
Since you mentioned deleting duplicate JAR files, it's important to ensure that you have the correct and compatible versions of the SAML library JAR files. Remove any conflicting or unnecessary JAR files that might be causing conflicts.