How To Fix G01521 - Function can be carried out once at the beginning of a transaction

SAP Error Message - Details

• Message type: E = Error

• Message class: G01 - SAP Consolidation

• Message number: 521

• Message text: Function can be carried out once at the beginning of a transaction

What causes this issue?

The entry of posting is already running. For this reason no new
selection can be made by double clicking on a document type or a held
document.

System Response

The current entry of posting will be continued.

How to fix this error?

If you have selected the wrong document type by mistake, or want to use
a different held document, end the entry which is running and start it
again.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message G01521 - Function can be carried out once at the beginning of a transaction ?

  The SAP error message G01521, which states "Function can be carried out once at the beginning of a transaction," typically occurs when a function or operation is attempted more than once within a single transaction context where it is only allowed to be executed once. This is often related to processes that are designed to initialize or set up a transaction, and they should only be executed at the start.
  Causes:
  
  Repeated Execution: The function or transaction is being called multiple times within the same session or transaction.
  Incorrect Transaction Flow: The sequence of operations in the transaction is not being followed correctly, leading to an attempt to re-invoke a function that should only be called once.
  User Error: The user may be inadvertently trying to perform the same action multiple times, such as clicking a button or executing a command that triggers the function again.
  
  Solutions:
  
  Check Transaction Flow: Review the sequence of operations in your transaction. Ensure that the function is only called once at the beginning and that subsequent operations do not attempt to re-invoke it.
  Debugging: If you have access to debugging tools, you can trace the execution of the transaction to identify where the function is being called multiple times.
  User Training: If the error is due to user actions, consider providing training or documentation to help users understand the correct process.
  Transaction Reset: If the transaction is in an inconsistent state, you may need to reset it or start a new session to clear the error.
  Consult Documentation: Refer to SAP documentation or help resources for the specific transaction or function you are working with to understand its intended use and limitations.
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any known issues or patches related to the specific transaction or function you are using.
  Transaction Codes: Familiarize yourself with the transaction codes involved and their expected behavior.
  Support Forums: Consider searching or posting on SAP community forums for additional insights from other users who may have encountered the same issue.
  
  If the problem persists after trying the above solutions, it may be beneficial to contact your SAP support team or consult with an SAP expert for further assistance.