Message type: E = Error
Message class:  PPC1DM - PP Backflush: Database Management and Communication 
Message number: 023
Message text: Production line already exists in this version
You are trying to introduce a line/reporting point structure to the ERP
system which already exists. Such a structure is identified via the
parameter LINEHEADER and LINEVERSION. The line/reporting point structure
&V1& with version number &V2& already exists and can therefore not be
saved.
The line/reporting point structure is not saved.
Backflushes for this line/reporting point structure are checked with the
already existing structure in the system.
Check the transferred parameters LINEHEADER and LINEVERSION. The value
of parameter LINEVERSION is probably too small.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message PPC1DM023 indicates that a production line you are trying to create or modify already exists in the current version of the data. This error typically occurs in the context of SAP's Production Planning (PP) or Advanced Planning and Optimization (APO) modules, where production lines are defined for planning and scheduling purposes.
Cause: Duplicate Entry: The most common cause of this error is that there is already an existing production line with the same identifier in the system for the current version. Versioning Issues: If you are working with different versions of data, you might be trying to create a production line in a version where it already exists. Data Migration or Upload Issues: If you are importing or migrating data, there may be duplicates in the data being uploaded.
Solution: Check Existing Production Lines: Navigate to the relevant transaction (e.g., transaction code PPC1 or PPC2) and check the list of existing production
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