Diagnosis
You wish to change a purchasing document that is subject to a releasestrategy.
Your changes may cause a release procedure that has already started tobe interrupted because the document may fall under a different releasestrategy after you have changed it. In this case, any already-effectedreleases will be cancelled by the system and a new release procedurewill commence.

Procedure
Take a look at the current status using the function "Releaseinformation".