After goal creation with focus “event related stuff” (event cat, action, name, …) if you want to switch back to another goal type (user vists a given URL) it always throws an error, that the (apparently set event value in the background?) value set needs to be set… You have to delete the goal an re-create a new one. Screenshot shows the error message after the goal was switched to URL based conditions again.
It seems like the UI is overly pedantic here:
When you used the event type, you ticked
Use the event value (if it exists) as the goal conversion revenue. below. When you change the goal type, this checkbox is hidden, but is still ticked, but doesn’t make any sense anymore and the server rejects the value.
As a workaround you can untick this checkbox before you change the goal type.
I have created an issue for this here: