How To Fix MM311 - The number & proposed by the customer exit already exists

SAP Error Message - Details

• Message type: E = Error

• Message class: MM - Messages for material master maintenance and Customizing

• Message number: 311

• Message text: The number & proposed by the customer exit already exists

What causes this issue?

You wanted to create a material and assign the material number
yourself. However, your system is set up such that externally assigned
material numbers are modified internally. In this case, the resulting
number &V1& already exists.

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?

You have the following options:
Choose a different number.
Ask your system administrator to check the source code of the customer
exit.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message MM311 - The number & proposed by the customer exit already exists ?

  The SAP error message MM311, which states "The number & proposed by the customer exit already exists," typically occurs in the context of material management, particularly when dealing with number ranges or unique identifiers for materials, vendors, or other entities in the system. This error indicates that the system is trying to assign a number that is already in use, which violates the uniqueness constraint.
  Cause:
  
  Duplicate Number Assignment: The most common cause of this error is that the system is attempting to assign a number that has already been assigned to another object (e.g., material, vendor).
  Custom Logic in Customer Exit: If there is a custom customer exit implemented that generates or proposes numbers, it may be incorrectly configured to generate a number that already exists.
  Number Range Configuration: The number range settings for the relevant object may not be properly configured, leading to conflicts in number assignment.
  
  Solution:
  
  Check Existing Numbers: Verify the existing numbers in the relevant table (e.g., MARA for materials) to see if the proposed number is indeed already in use.
  Review Customer Exit Logic: If a customer exit is involved, review the code to ensure that it correctly generates unique numbers. You may need to modify the logic to avoid proposing numbers that already exist.
  Adjust Number Ranges: Check the configuration of number ranges in the SAP system. Ensure that the number range is set up correctly and that there are sufficient available numbers in the range.
  
  You can do this by navigating to SPRO > IMG > Materials Management > Material Master > Basic Settings > Number Ranges.
  
  
  Use a Different Number: If possible, manually assign a different number that does not conflict with existing entries.
  Debugging: If the issue persists, consider debugging the process to identify where the number is being generated and why it is conflicting.
  
  Related Information:
  
  Transaction Codes: You may need to use transaction codes like MM01 (Create Material), MM02 (Change Material), or MM03 (Display Material) to interact with material master data.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message. SAP frequently updates its knowledge base with solutions for common problems.
  Documentation: Review SAP documentation related to number ranges and customer exits for more detailed guidance on configuration and troubleshooting.
  
  By following these steps, you should be able to identify the root cause of the MM311 error and implement a solution to resolve it.