How To Fix WRF_APC321 - Target purchasing list &1 is already locked by user &2

SAP Error Message - Details

• Message type: E = Error

• Message class: WRF_APC - Messages for Operational Assortment Planning and Control

• Message number: 321

• Message text: Target purchasing list &1 is already locked by user &2

What causes this issue?

Purchasing list &V1& is currently being processed by user &V2& and
therefore cannot be changed.
Purchasing list items cannot be inserted into this purchasing list.
Items cannot be transferred or copied to this purchasing list.
Data transfer from the Layout Workbench to this purchasing list is not
possible.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Try again later when this purchasing list is no longer in use, or ask
the user who is currently processing it to exit so that you can perform
the desired action.
If you transfer data from the Layout Workbench to the corresponding
purchasing list, there are certain circumstances where it can appear
that you have locked yourself out. This can happen, for example, if you
release a Layout Module Version (which implicitly triggers a transfer of
data) and then choose the <LS>OAPC Transfer</> button immediately
afterwards (which explicitly triggers a transfer of data). The implicit
transfer might not yet be completed at the moment you are requesting the
explicit transfer. If this happens, just ignore the message and continue
processing.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.