4 answers
I'd start by checking any Flows, Process Builders, or Apex Triggers that run when an Opportunity is updated. A Field Integrity Exception usually means some automation is trying to save an invalid value.
The numbers after the record ID aren't usually very useful for troubleshooting. The best next step is to enable a Debug Log, reproduce the error, and see which automation is failing.
Does the error happen for every stage change or only for a specific stage? That can help narrow it down.