How To Fix ME791 - Order units differ

SAP Error Message - Details

• Message type: E = Error

• Message class: ME - Purchasing: General Messages

• Message number: 791

• Message text: Order units differ

What causes this issue?

The supplier has sent you an order acknowledgment relating to purchase
order no. &V1&, item &V2&, via EDI. However, the order unit specified in
the IDoc differs from the one shown in the PO.

How to fix this error?

Check the order units in the IDoc and in the purchase order:
<DS:TRAN.ME23N>Display purchase order</>.
If necessary, change the purchase order.
Or get the supplier to change the IDOC.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message ME791 - Order units differ ?

  The SAP error message ME791 ("Order units differ") typically occurs in the context of purchasing or inventory management when there is a mismatch between the units of measure for an order and the units of measure defined for the material or product in the system. This can happen during various transactions, such as creating a purchase order, goods receipt, or inventory transfer.
  Cause:
  
  Unit of Measure Mismatch: The unit of measure specified in the purchase order or transaction does not match the unit of measure defined in the material master for the item.
  Conversion Issues: If there are conversion factors defined between different units of measure, they may not be set up correctly, leading to discrepancies.
  Configuration Issues: The settings in the material master or purchasing info records may not be aligned, causing the system to flag the difference.
  Document Type Settings: Certain document types may have specific requirements for units of measure that are not being met.
  
  Solution:
  
  
  Check Material Master: 
  
  Go to the material master record (transaction code MM03) and verify the units of measure defined for the material. Ensure that the base unit of measure and any alternative units of measure are correctly set up.
  
  
  
  Review Purchase Order:
  
  Check the purchase order (transaction code ME23N) to ensure that the unit of measure used matches the unit of measure in the material master. If necessary, change the unit of measure in the purchase order to match.
  
  
  
  Adjust Conversion Factors:
  
  If you are using alternative units of measure, ensure that the conversion factors are correctly defined in the material master. You can do this in the purchasing view of the material master.
  
  
  
  Check Info Records:
  
  If you are using purchasing info records (transaction code ME13), verify that the unit of measure in the info record matches the unit of measure in the material master.
  
  
  
  Consult Configuration:
  
  If the issue persists, consult with your SAP configuration team to review the settings related to units of measure in the system. This may involve checking the configuration in SPRO (Customizing) under Materials Management.
  
  
  
  Testing:
  
  After making the necessary adjustments, test the transaction again to ensure that the error is resolved.
  
  
  
  Related Information:
  
  Unit of Measure (UoM): In SAP, each material can have multiple units of measure, including base unit, order unit, and sales unit. Understanding how these units interact is crucial for avoiding errors.
  Transaction Codes:
  
  MM03: Display Material Master
  ME23N: Display Purchase Order
  ME13: Display Purchasing Info Record
  
  
  Documentation: Refer to SAP Help documentation for detailed information on units of measure and their configuration.
  
  By following these steps, you should be able to identify and resolve the ME791 error in SAP.