If you have the In Place Records Management feature enabled for your site collection and you declare a list item as a record, SharePoint will "crash" if you try to add an attachment to the record. I know it does not make much sense to add an attachment to a declared record, but SharePoint will not prevent you from trying (if you don't notice it has been declared a record for example). For any other changes you try to make to the record SharePoint will display a nice little message that the record is locked and cancel the event, but for some reason adding an attachment instead causes a crash.
Steps to reproduce:
1. Activate the "In Place Records Management" site collection feature
2. Create a custom list
3. In the list settings, allow manual declaration of records in the record declaration settings
4. Create a new list item
5. Declare the new list item as a record
6. Edit the item, add an attachment, and attempt to save the change.
SharePoint will crash to a stack trace instead of providing a graceful error message
