KB-1725 Expression evaluation error in rule 'X' at function fn!webservicequery


Users are faced with an "Error Evaluating UI Expression" pink box error when attempting to access any interface that utilizes the webservicequery() function. The following exception is printed in the application server log:

com.appiancorp.core.expr.exceptions.ExpressionRuntimeException$AppianExceptionProvider: Expression evaluation error in rule '<RULE_NAME>' (called by rules '<RULE_NAME>' > '<RULE_NAME>' > '<RULE_NAME>') at function fn!webservicequery [line 2]: The operation [...] is not present in the binding [...]. Available operations in that binding: [...] (APNX-1-4198-000)


The data types required by the web service are created if they are not already present in the system the first time the expression function is invoked. If one or more data types already exists with the same name and namespace but with a different structure, the function returns the error above. This is further explained in the Notes section of the webservicequery() Function documentation.


  1. Create a test process model with the Call Web Service smart service and point it to the WSDL.
  2. Use the Get/Refresh Services button on the Call Web Service smart service node to refresh the data types.
  3. Publish the process model. (Note: the process model must be published in order to complete the update. You can optionally delete the process model afterward).

Note: If this is occurring in an environment with multiple application servers, perform a rolling restart of the application servers after following the steps above.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: March 2019