How To Fix 5P037 - Only the characters X ' ' are allowed (' ' not possible in variable key)

5P037 - Overview

• Message type: E = Error

• Message class: 5P - Error Messages for Schema, Pers.Calc.Rule and Feature Checks

• Message number: 037

• Message text: Only the characters X ' ' are allowed (' ' not possible in variable key)

What causes this issue?

This error can occur during an operation or in the variable key.
In both cases, it means that you have used incorrect characters.

How to fix this error?

Read the related documentation and correct the entry.
You cannot use " " for the query in the variable key. The following
two entries are required:
one entry with "X" as the value,
one entry with "*" as the value which represents the "OTHERS".
The "*" entry then implicitly represents a query using " ".

Error message extract from SAP system. Copyright SAP SE.

5P037 - Details

• The SAP error message 5P037 indicates that there is an issue with the input of a variable key in a certain context, typically related to the use of characters in a selection screen or a data entry field. The message states that only the characters 'X' (for true) and ' ' (space for false) are allowed, and that a space (' ') is not possible in the variable key.
  
  Cause:
  
  Invalid Input: The variable key is expected to be either 'X' or a blank space. If any other character is entered, this error will occur.
  Configuration Issue: There may be a configuration issue in the way the variable key is defined or used in the program or report.
  Data Entry Error: Users may inadvertently enter invalid characters or spaces that are not allowed.
  
  
  Solution:
  
  Check Input: Ensure that the input for the variable key is strictly 'X' or a blank space. Remove any other characters that