How To Fix 55401 - Internal error: message classification &1, parentheses

55401 - Overview

• Message type: E = Error

• Message class: 55 - Messages for development class EENO

• Message number: 401

• Message text: Internal error: message classification &1, parentheses

What causes this issue?

Message classification (&V1&) for the IS-U message object has an
invalid format. This is a program error that can only be rectified by
SAP.

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?

Note the following:
transaction
entries leading to the error
message text
and send a problem message to SAP.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message 55401 - Internal error: message classification &1, parentheses ?

  The SAP error message 55401, which states "Internal error: message classification &1, parentheses," typically indicates an internal inconsistency or issue within the SAP system. This error can arise from various underlying causes, including:
  Causes:
  
  Data Inconsistency: There may be inconsistencies in the data being processed, such as missing or malformed entries.
  
  Configuration Issues: Incorrect configuration settings in the system can lead to unexpected behavior and errors.
  Custom Code: If there are custom developments or enhancements in the system, they might not be handling certain scenarios correctly.
  System Bugs: There could be bugs in the SAP software version you are using, which may have been addressed in later patches or updates.
  
  Solutions:
  
  Check for Data Issues: Review the data being processed when the error occurs. Look for any anomalies or inconsistencies that could be causing the issue.
  Review Configuration: Ensure that all relevant configurations are set up correctly. This includes checking transaction codes, message classes, and any related settings.
  Debugging: