These problems are not related to a concrete Jira issue but are rather general.

411 - Length required
All fields have English names although Jira is in a different language
Authentication with an external Jira fails
Exception: ServiceLocatorImpl has been shut down
Sync info panel displays wrong synchronization name, and no link to partner project
Server is not reachable - how to fix it
Changes are not being synchronized
Can't change the synchronization user
Recently created issue types, fields, etc. are not available when editing configuration