How To Fix GB129 - Substitution name must begin with a letter

SAP Error Message - Details

• Message type: E = Error

• Message class: GB - Messages used by the Boolean code generator

• Message number: 129

• Message text: Substitution name must begin with a letter

What causes this issue?

The name of the substitution must begin with a letter (and not with a
number). You can use the following letters:
ABCDEFGHIJKLMNOPQRSTUVWXYZ

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?

Re-enter the name of the substitution.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message GB129 - Substitution name must begin with a letter ?

  The SAP error message GB129, which states "Substitution name must begin with a letter," typically occurs in the context of SAP's substitution functionality, often used in financial or controlling modules. This error indicates that the name you are trying to use for a substitution does not conform to the naming conventions required by SAP.
  Cause:
  
  Invalid Naming Convention: The substitution name you are trying to create or use does not start with a letter. SAP requires that all substitution names begin with an alphabetic character (A-Z).
  Typographical Error: There may be a typographical error in the name you are entering, such as starting with a number or a special character.
  Copy-Paste Issues: If you copied the name from another source, it might contain hidden characters or spaces that are not visible.
  
  Solution:
  
  Check the Name: Ensure that the substitution name you are entering starts with a letter. For example, instead of "1Substitution", use "Substitution1".
  Remove Special Characters: Make sure there are no special characters or spaces at the beginning of the name.
  Follow Naming Conventions: Familiarize yourself with the naming conventions used in your organization or project. Typically, names should be descriptive and follow a consistent format.
  Re-enter the Name: If you suspect there might be hidden characters, try typing the name manually instead of copying and pasting it.
  
  Related Information:
  
  Substitution in SAP: Substitution is a feature in SAP that allows you to replace certain values in documents or transactions with other values based on predefined rules. This is often used in financial reporting and controlling.
  Transaction Codes: You may be using transaction codes like OB28 (for defining substitutions) or similar, where this error can occur.
  Documentation: Refer to SAP Help documentation or your organization's SAP guidelines for more information on naming conventions and substitution rules.
  
  If you continue to experience issues after following these steps, consider reaching out to your SAP administrator or support team for further assistance.