How To Fix ATP_SE021 - Reference mix not allowed (first document &1, second document &2)

SAP Error Message - Details

• Message type: E = Error

• Message class: ATP_SE - Message class for ATP-Services

• Message number: 021

• Message text: Reference mix not allowed (first document &1, second document &2)

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

Unfortunately, there isn't any extra information in this error notice.

What else can you do?

First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).

Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.

You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.

Smart SAP Assistant

• What is the cause and solution for SAP error message ATP_SE021 - Reference mix not allowed (first document &1, second document &2) ?

  The SAP error message ATP_SE021, which states "Reference mix not allowed (first document &1, second document &2)," typically occurs in the context of Advanced Planning and Optimization (APO) or when dealing with ATP (Available-to-Promise) checks in SAP. This error indicates that there is an issue with the way two documents (such as sales orders, purchase orders, or stock transfer orders) are being referenced or mixed in the system.
  Cause:
  
  
  Document Type Mismatch: The error often arises when there is an attempt to reference two documents of different types that are not allowed to be mixed. For example, you might be trying to reference a sales order and a purchase order together, which is not permitted.
  
  
  Configuration Issues: There may be configuration settings in the system that restrict the mixing of certain document types. This could be due to settings in the ATP configuration or in the document type settings.
  
  
  Data Integrity Issues: There could be issues with the data integrity or consistency in the documents being referenced, leading to the system rejecting the operation.
  
  
  Solution:
  
  
  Check Document Types: Review the document types involved in the error message. Ensure that you are not trying to mix incompatible document types. If necessary, separate the operations to handle each document type independently.
  
  
  Review Configuration Settings: Check the configuration settings in the SAP system related to ATP and document types. Ensure that the settings allow for the intended operations. This may involve consulting with your SAP Basis or configuration team.
  
  
  Data Validation: Validate the data in the documents to ensure that there are no inconsistencies or errors. This may involve checking for missing fields, incorrect values, or other data-related issues.
  
  
  Consult SAP Notes: Look for relevant SAP Notes or documentation that may address this specific error. SAP frequently updates its knowledge base with solutions to common issues.
  
  
  Testing: After making any changes, conduct thorough testing to ensure that the issue is resolved and that the system behaves as expected.
  
  
  Related Information:
  
  SAP Documentation: Refer to the official SAP documentation for ATP and APO for more detailed information on document handling and configuration.
  SAP Community: Engage with the SAP Community forums to see if other users have encountered similar issues and what solutions they have found.
  Transaction Codes: Familiarize yourself with relevant transaction codes such as /SAPAPO/ATC for checking ATP settings or /SAPAPO/SDP94 for planning board functionalities.
  
  If the issue persists after trying the above solutions, it may be beneficial to involve your SAP support team or consult with an SAP expert for further assistance.