Hello Evangeline,
Have you checked your java libraries in eclipse?
When you update a module there is a chance you receive an up-to-date library that is required for the module to work, but the app is already using an old library. If this is the case you need to remove the old library and leave only the new one to load.
Edit:
Here's a short guide from Mendix on the basics of Eclipse (https://docs.mendix.com/refguide/using-eclipse)
To check your libraries, in eclipse navigate to Project > Properties > Java build path and check if there's any duplicates with different versions
Hope this helps