I have a function that locks down the opportunity based on several conditions.
When a user uses split view and tries to sort the data grid they get an Exception error and this is one error I have never seen when using custom code. Usually you will get a line error telling you exactly where something is failing.
When I comment out the opp lock code the error does not occur anymore. I've checked and checked the code again and I'm sure this should work. This error only occurs when using split view on the opportunity.
As you learn which part of your code is causing the issue, I suggest that you just put a breakpoint at the beginning of that section and then debug it line by line until the error happens - then you'll isolate the line which blows up and should be able to work out why.