BIP2534
Severity
20 : Error
Message
(<insert_1>, <insert_2>) : The dynamic field reference does not resolve to a modifiable quantity.
Explanation
The dynamic field reference supplied must resolve to a modifyable quantity (a declared variable or a field in a modifyable message) as the usage implies that its value is to be changed.
Response
Correct the syntax of your ESQL expression in node <insert_1>, around line and column <insert_2>, then redeploy the message flow.