Hi there, this sounds like a corrupted session in MongoDB. You could try dropping the documents in the sessions collection to see if that does the trick.
Also, I want to mention this particular article: How to Post a Question in the Community that Gets Responses. We’ve put that together to make the process of asking and answering questions a bit less onerous for forum users. In the future, it would help if you can do things like:
- Tell us how you upgraded, or provide steps for us to try and retrace
- Surround your output with ``` to make it easier to read