No uniform result typing is possible

What causes this issue?

The return values of the WHEN conditions of the CASE expressions differ
in length.

System Response

The system is unable to determine any uniform result typing for the CASE
expression.

How to fix this error?

This message can have one of the following meanings:
If it is necessary to type the CASE expression completely, you must
ensure that all return values of the WHEN conditions have the same
length, output length and number of decimal places.
If it is not necessary to type the CASE expression completely, you can
ignore the message.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.