Missing issue type

Symptoms

An issue does not get synchronized and an error appears in the troubleshooting section with the category Incoming Issue error and a message such as There is no issue type mapping defined for id: 10021.

Cause

A possible cause for this problem is that an issue type which is configured in Issue Types section has been deleted from one of the Jira instances.

Resolution

1. Clear Backbone cache in order to see which issue type mapping is incorrect.
2. Try to fix the problem by changing / replacing the issue type configuration which is linked to the deleted Issue Type.