This error will either appear in your Dashboard's activity feed or in your Transaction Report.
Error Message Example
422 Unprocessable Entity / contact With Id = 825bf757-59e7-e711-80e2-005056b47943 Does Not Exist /
This means that you removed a record from your Dynamics CRM yet Formstack Sync still has it stored in our INDEX so we are still trying to process updates to this record.
How to Resolve
In some cases customers may not necessarily want this issue to be resolved. If you removed the record from Dynamics it was likely due to a specific reason and therefore you may not want it added back. If this is the case, then there are no actions you need to take with this error.
However, there will likely come a time when you want to run a reset for your Formstack Sync integration. This process will remove the historical record from Formstack Sync and therefore freeing up the record from your other system to sync back over if it passes one of your Workflow rules. To avoid this from happening, we recommend putting in place a process such as the one we outline in this help article.