I am trying to create an ECA workflow to assign a custom role on user registration based on drop down field selection.

User selects Value 1 from Custom_Field on registration form, clicks Register, Custom_Role gets assigned.

Can someone point me to what the ECA workflow should look like, either Classic or BPMN version?

ChatGPT has provided dozens of suggestions, none have worked.

I could have built this with Rules module without any help but ECA has completely lost me.

Drupal version is 10.6.1. The site gives this WSOD:

The website encountered an unexpected error. Try again later.

It was a test site with about a month of work done. No backups, never thought this could be a problem with Drupal in 2026.

Un-installed rules module with composer but error remains.

Is there any chance of recovery?