Dynamics ax a key with the name %1 already exists

Today I had to fix a bug in some custom code in Dynamics Ax 2009, we had an error from the JournalTransList class that stated “A key with the name %1 already exists.”

  • Cause: A custom field on the WMSJournalTrans table that was extending from LineNum
  • Reason: The JournalTransList has methods to check if the primary index on the actual table won’t be violated, therefore it seems to look for all fields that extend from LineNum.
  • Solution: Create you’re custom EDT that extends from LineNum and add that one to the table, it’s a best practice but who thought this could be so critical :p


  1. Thanks a million! This problem still exists in Microsoft Dynamics 365 for Finance and Operations. I used steps to solve for another client as well.

  2. Hi Kevin,

    Thanks a ton. this really save me hours of debugging. i have custom fields on prod journal bom and same scenario. Just change the edt and and error go way. i never thought this would be the reason.

    1. Hi Hammad,

      I’m glad it worked!
      On what version did you have this? I’m curious to see how relevant the post still is 🙂

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