How To Fix SY449 - You cannot use this function with key tables

SY449 - Overview

• Message type: E = Error

• Message class: SY - ABAP/4 system messages

• Message number: 449

• Message text: You cannot use this function with key tables

What causes this issue?

You cannot insert or append lines to hashed or sorted tables in the
Debugger. You can only change the key fields of these tables.

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?

Error message extract from SAP system. Copyright SAP SE.

SY449 - Details

• The SAP error message SY449, which states "You cannot use this function with key tables," typically occurs when you are trying to perform an operation that is not allowed on key tables in SAP. Key tables are those that have a primary key defined and are often used in database operations where the integrity of the data is crucial.
  
  Cause:
  The error usually arises in the following scenarios:
  
  Inappropriate Functionality: You are trying to use a function or transaction that is not compatible with key tables. This could be due to attempting to modify, delete, or perform certain operations that are restricted on key tables.
  Incorrect Table Type: The table you are working with is defined as a key table in the data dictionary, and the operation you are attempting is not permitted for that type of table.
  Custom Code Issues: If you are using custom ABAP code, there may be logic that incorrectly attempts