There are no issue types with compatible field configuration and/or workflow associations.

Question

Any attempt to edit a SUBTASK results in the following error message upon clicking "Save"

There are no issue types with compatible field configuration and/or workflow associations. 
 The issue type can only be changed by moving this issue.

Can anyone point me towards the correct thing to look at for this issue?

Jobin Kuruvilla [Adaptavist] · Accepted Answer

Check in the schemes used by your project, field configuration scheme, workflow scheme etc, and see if subtask is missing out on any of them.