How To Fix TPDA159 - This action is not possible here (for example, in a conversion exit).

TPDA159 - Overview

• Message type: E = Error

• Message class: TPDA - Debugger

• Message number: 159

• Message text: This action is not possible here (for example, in a conversion exit).

What causes this issue?

This action in the debugger is not always possible.
In some situations ABAP is called directly from the kernel, for example
with a conversion exit (function modules CONVERSION_EXIT_*_OUTPUT or
CONVERSION_EXIT_*_INPUT).
You can recognize this situation if a direct call for the relevant entry
cannot be identified in the ABAP stack (for example, the ABAP stack
shows that a function module CONVERSION_EXIT_*_OUTPUT is called from a
WRITE statement).
If there is one of these entries on the ABAP stack, this action cannot
be used here.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

TPDA159 - Details

• The SAP error message TPDA159, which states "This action is not possible here (for example, in a conversion exit)," typically occurs when a certain operation or function is attempted in a context where it is not allowed. This can happen in various scenarios, such as when using conversion exits, field exits, or certain function modules that are not permitted in specific contexts.
  
  Cause:
  
  Context Restriction: The error usually arises when a function or method is called in a context where it is not applicable. For example, trying to perform a certain operation in a conversion exit where it is not allowed.
  Invalid Data Handling: Attempting to manipulate data in a way that is not supported by the current processing logic or data type.
  Incorrect Function Usage: Using a function or method that is not designed to be used in the current context, such as trying to access database records or perform calculations in a