How To Fix AH491 - Units of measurement do not match

SAP Error Message - Details

• Message type: E = Error

• Message class: AH - IS-U billing (master data)

• Message number: 491

• Message text: Units of measurement do not match

What causes this issue?

You have entered an inadmissible discount or price in fact maintenance.
Unit of measurement &v2& for the operand &v1& in the facts is different
to the unit of measurement &v3& for the discount or for the price.

System Response

How to fix this error?

Choose an appropriate discount or price using the input help in the
field <LS>Discount</> or <LS>Price</>.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message AH491 - Units of measurement do not match ?

  The SAP error message AH491, which states "Units of measurement do not match," typically occurs when there is a discrepancy between the units of measurement used in different parts of a transaction or document. This can happen in various scenarios, such as when creating purchase orders, sales orders, or during inventory management.
  Causes of AH491 Error
  
  
  Mismatched Units: The most common cause is that the units of measurement for the materials or products involved in the transaction do not match. For example, if you are trying to order a product measured in kilograms but the system expects it in grams.
  
  
  Conversion Issues: If there are conversion factors defined for the units of measurement, and they are not set up correctly, this can lead to mismatches.
  
  
  Material Master Data: The material master data may have inconsistent unit definitions. For instance, the base unit of measure might differ from the unit of measure used in the transaction.
  
  
  Configuration Issues: There may be configuration settings in the SAP system that are not aligned with the units of measurement being used.
  
  
  Solutions to AH491 Error
  
  
  Check Units of Measurement: Verify the units of measurement for the materials involved in the transaction. Ensure that they are consistent across all relevant documents (e.g., purchase orders, sales orders, etc.).
  
  
  Review Material Master Data: Go to the material master record and check the units of measurement defined there. Ensure that the base unit of measure and any alternative units of measure are correctly set up.
  
  
  Adjust Conversion Factors: If conversion factors are being used, ensure that they are correctly defined in the system. You can check this in the material master under the "Units of Measure" view.
  
  
  Transaction Review: Review the transaction you are trying to execute. Make sure that all line items and their respective units of measurement are consistent.
  
  
  Consult Configuration Settings: If you have access to the configuration settings, check the settings related to units of measurement in the relevant modules (e.g., MM, SD). Ensure that they are set up correctly.
  
  
  User Input: If the error occurs due to user input, ensure that users are trained to select the correct units of measurement when entering data.
  
  
  Related Information
  
  
  SAP Notes: Check SAP Notes for any known issues or patches related to this error. SAP frequently updates its knowledge base with solutions to common problems.
  
  
  Documentation: Refer to SAP documentation for detailed information on units of measurement and how they are managed within the system.
  
  
  Support: If the issue persists after checking the above points, consider reaching out to your SAP support team or consulting with an SAP expert for further assistance.
  
  
  By following these steps, you should be able to identify and resolve the cause of the AH491 error in your SAP system.