Error when resetting password of basic user using admin console

Hi all,

One of our basic users have forgotten his password. First, I've asked him to reset his password from the log-in page, but he reported that he's not getting an email (not even in his spam folder).

So I tried resetting his password using the admin console but I'm getting this system error.

Here's the error extracted from our logs:

Caused by: com.appiancorp.core.expr.exceptions.ExpressionRuntimeException$AppianExceptionWithRootCauseProvider: Expression evaluation error [evaluation ID = I9TTZ670]: An error occurred while attempting to store into the following variables: [local!passwordResetWriter]. Details: [[local!passwordResetWriter:The user [redacted@sample.com] does not have sufficient privileges to perform the requested action because they are not in any role.]] (APNX-1-4245-002)

We're currently using Appian version 18.4.

Thanks!