We have a custom trigger on the SBQQ Quote object that deletes the auto-generated opportunity and associates an existing opportunity to the newly created quote. This was working in the sandbox but not in production. We were getting the following error:
"Can't save record. This record has been changed and saved in a different session. Related the record and try again." Warning. Failed to revert changes. Please check data integrity.
We also noticed that the quote wasn't created by the same user that amended the contract. It was created by the user that had been authorized in the CPQ configuration.