Optimization of Case expression and Join used is not possible.

What causes this issue?

The planned optimization for dependent joins using the annotation
@ABAPCATALOG.COMPILER.CASEJOIN is not possible in this case.
Due to the restrictions listed below, the optimization action is not
possible:
Client-independent data sources within the CASE expression
Outdated annotation for client handling The annotations to be used are
@ClientHandling.type or @ClientHandling.algorithm
Complex condition after WHEN
The restriction for individual case-when clauses is in the form <(>
<<)>Element> = literal values
Complex expression after THEN; only path expressions of length 2 are
allowed here.
Path expressions with different outbound data sources
Combination of path expressions with local defined associations and
non-local defined associations
Solely searched-case expressions are supported.
An association is used multiple times within a SELECT command;
optimization of the conditional join operations is not advantageous.
In this case, the optimization cannot be applied due to restriction
number &V1&.

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.