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

SAP Error Message - Details

• 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.