KB-1046 "No valid recipients resolved" error thrown when using Send Email

Symptoms

When using the Send Email Smart Service nodes in a process, emails are not sent as expected. The following error is seen in the application server log:

 INFO  [stdout\] (Appian Work Item - 1 - ProcessExec00 : 
UnattendedJavaActivityRequest) 
    
[Appian Work Item - 1 - ProcessExec00 : UnattendedJavaActivityRequest] 
ERROR com.appiancorp.process.runtime.activities.SendEmailActivity - java.lang.Exception: No valid recipients resolved

In addition, the following alert is seen in Appian Designer:

With these errors, the process instance will fail.

Cause

The "To" field of the "Send Email" node is not of the type emailRecipient. This can happen, for example, if there is a process variable that is of a type other than emailRecipient (such as Text) in the "To" field.

Action

Cast the To field value to the emailRecipient type by using the toemailrecipient() function.

Affected Versions

This article applies to all versions of Appian.