Diagnosis
There are two possible reasons for the error:

• You attempted to edit a query that was already being edited by another
user.

• You attempted to execute a query being edited by another user. This
user has already saved a new version of the query, but no suitableprogram has yet been generated. No program can be generated until theuser has finished editing the query.

Procedure
You cannot edit or execute the query until the other user has finished.