Message type: E = Error
Message class:  APPL_MM_PUR_SOS_SL - Messages for Source List 
Message number: 001
Message text: Active Source List exists for Material :&1 Plant:&2 Combination
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The SAP error message APPL_MM_PUR_SOS_SL001 indicates that there is an active source list for a specific material and plant combination. This error typically arises when you are trying to perform an action that requires the source list to be inactive or when you are attempting to delete or modify a source list entry that is currently active.
Cause: Active Source List: The primary cause of this error is that there is an active source list entry for the specified material and plant combination. The system does not allow certain operations (like deletion or modification) on active source lists. Data Integrity: SAP enforces data integrity rules, and having an active source list means that the system expects that the source list is being used for procurement processes.
Solution: To resolve this error, you can take the following steps: Check the Source List: Go to transaction ME03 (Display Source List) and enter the material number and plant to check
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