How To Fix GB309 - Expression with subfield of field & in table & not permitted.

GB309 - Overview

• Message type: E = Error

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

• Message number: 309

• Message text: Expression with subfield of field & in table & not permitted.

What causes this issue?

You used a field for which a conversion routine is stored.

System Response

Processing is terminated.

How to fix this error?

Work with a user exit that calls up the conversion routine. In this
exit, you can use offset and length to manipulate parts of the external
representation of the field. (The external representation is the form
in which the field contents appear on the screen.)

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message GB309 - Expression with subfield of field & in table & not permitted. ?

  The SAP error message GB309 indicates that there is an issue with the use of subfields in a field within a specific table. This error typically arises when you are trying to access or manipulate a subfield of a field in a way that is not permitted by the system's data structure or rules.
  
  Cause:
  
  Subfield Access: The error occurs when you attempt to access a subfield of a field that is not allowed in the context of the operation you are performing. This can happen in various scenarios, such as during data processing, report generation, or when writing custom ABAP code.
  Data Structure: The underlying data structure of the table may not support subfield access for the specified field. This can be due to the field being defined as a simple data type rather than a structured type.
  Incorrect Syntax: There may be a syntax error in the code where the subfield is