Diagnosis
There are two possible causes for the error:
1. You tried to edit a query, but this is not possible at the momentbecause another user is already editing this query.
2. You tried to execute a query, but at the moment this query is beingedited by another user. This user already saved a new version of thequery, but a suitable program was not yet generated. Generation is notpossible as long as the other user is still editing the query.

Procedure
You can only edit or execute the query when the other user hasfinished working with the query.