I'm having some trouble implementing a custom FormAction to an authentication Flow.  I've hit a wall and decided to step-back and make sure that I am performing the correct steps in the Keycloak admin interface to add a FormAction to a flow.  As a test, I want to remove and then add the stock "Profile Validation" execution to a Registration flow.  I'm getting a (hopefully reproducible) exception performing the following steps.  I'm attempting to follow the documentation in section "34.5.3 Adding FormAction to the Registration Flow"

1.  Click main "Authentication" link.

2.  Select "Registration" flow

3.  Press "Copy" button to get a flow I can edit

4.  Name the copy "test" 

5.  From the "Actions" pull down for the "Profile Validation" execution - choose "delete"

6.  From the "Actions" pull down for the "Test Registration Form" choose "Add Execution"

7.  Select the "Profile Validation" provider and press "Save"

I get the message "Error! An unexpected server error has occurred."  

Is this reproducible?  Am I missing a step here or perhaps not understanding something? 

Thanks for your help!

Kyle

Here is the stacktrace from keycloak logs: