TCL error

Thanks for detailed reply , one thing we never had these logs earlier , we have started getting these logs when we placed another irule with the existing irule under the VS existing irule when HTTP_REQUEST { if {[HTTP::header exists X-Forwarded-For]}{ HTTP::header replace X-Forwarded-For [substr [IP::client_addr] 0 "%"] } else { HTTP::header insert X-Forwarded-For [substr [IP::client_addr] 0 "%"] } }

new irule added last week to function with existing irule when HTTP_REQUEST { if {([class match [IP::remote_addr] equals whitelist]) } { pool Pool_1 } else { HTTP::respond 503 content [b64decode [class element -name 0 DG_MAINTENANCE_HTML]] "Content-Type" "text/html" } }