How To Fix WL491 - Operator '&' not allowed or blank in expression '& & &'

SAP Error Message - Details

• Message type: E = Error

• Message class: WL - Workflow: run-time messages

• Message number: 491

• Message text: Operator '&' not allowed or blank in expression '& & &'

What causes this issue?

The operator &V1& is not supported.

How to fix this error?

The F4 input help in the Workflow Builder lists all operators which are
supported in the current release. Choose one of the operators allowed.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message WL491 - Operator '&' not allowed or blank in expression '& & &' ?

  The SAP error message WL491 indicates that there is an issue with the use of the logical operator & in an expression within a selection screen or a report. This error typically arises when the expression is not correctly formed, leading to an invalid logical operation.
  Cause:
  
  
  Incorrect Use of Logical Operators: The error occurs when the logical operator & (AND) is used incorrectly in an expression. This can happen if:
  
  There are too many & operators without corresponding conditions.
  One or more of the conditions are blank or not defined.
  The syntax of the expression is incorrect.
  
  
  
  Blank Conditions: If any of the conditions in the expression are blank, the system cannot evaluate the expression properly, leading to this error.
  
  
  Solution:
  
  
  Check the Expression: Review the expression where the error occurs. Ensure that:
  
  Each & operator is followed by a valid condition.
  There are no extra & operators without corresponding conditions.
  
  
  
  Define All Conditions: Make sure that all conditions in the expression are defined and not left blank. If a condition is optional, consider using a different approach to handle it.
  
  
  Syntax Correction: Ensure that the syntax of the expression is correct. For example, if you are using multiple conditions, they should be properly structured, such as:
  IF condition1 AND condition2 AND condition3.
  
  
  Debugging: If you are unable to identify the issue, consider using debugging tools to step through the code and see where the expression is being evaluated.
  
  
  Consult Documentation: If you are still facing issues, refer to SAP documentation or community forums for additional insights on the specific context of your error.
  
  
  Related Information:
  
  Logical Operators in ABAP: In ABAP, logical operators include AND, OR, and NOT. Understanding how to use these operators correctly is crucial for building valid expressions.
  Selection Screens: If this error occurs in a selection screen, ensure that all fields are properly defined and that the logic for enabling/disabling fields is correctly implemented.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message, as there may be specific fixes or recommendations provided by SAP.
  
  By following these steps, you should be able to resolve the WL491 error and ensure that your expressions are correctly formed.