An issue does not get synchronized and appears in the troubleshooting section with the category Invalid JQL and a message containing, e.g. No issues have a parent epic with key or name 'Epic 1234'.
Similar error messages are:
- An issue with key 'KEY-123' does not exist for field 'issueKey'.
- An issue with key 'KEY-123' does not exist for field 'key'.
- An issue with key 'KEY-123' does not exist for field 'parent'.
You have setup an outgoing JQL filter which references an issue that does not exist anymore.
In order to resolve this problem:
- go to your configuration for limiting the issues and check that your JQL is valid. You probably have to delete the part of the JQL which references the issue which does not exist anymore.
- perform a resync for the affected issues.