How To Fix W8352 - Operator '&1' can only be applied to an object reference

SAP Error Message - Details

• Message type: E = Error

• Message class: W8 - Workflow: Expressions, data flow

• Message number: 352

• Message text: Operator '&1' can only be applied to an object reference

What causes this issue?

Operators 'EX' and 'NX' check for the existence (or non-existence) of
an object, for which a valid object reference must be available in the
container or must be accessible via a container expression.

How to fix this error?

Please ensure that the operand entered as expression 1 has an object
value. The object references are highlighted by a special symbol in the
expression tree.
The object reference to be checked must be entered as expression 1 (on
the left side).
You must not enter a multi-line container element, also if the line
type is an object reference.
Operators 'EX' and 'NX' only use one operand. Expression 2 is deleted
when operators 'EX' or 'NX' are inserted.

Error message extract from SAP system. Copyright SAP SE.