Linking invites to specific pages

OK, I'm not sure of the syntax.   I see the trigger:

 $_PLUGINS->trigger( 'onAfterUserRegistration', [ &$newUser, &$newUser, true ] );

Do I need a new CB field, cb_gj_id, to store the group id in so I can do

$newUser->set( 'cb_gj_id', $cbgroup );

Then in the AutoAction, how do I access that?  [var1_cb_gj_id]?

Yes, you'll need a way to pass the group id through so the auto action can do something with it and that should work fine.

OK, I see my custom registration is setting the new GJ ID field correctly and it shows up in his profile. The guest key user can join a guest key group.

The AutoAction I picked type "CB Groupjive",  condition was cb_gj_id of Active User not empty.

The Action Mode was Join Groups, Groups option "Specific Groups" and set to [var1_cb_gj_id].     Status: Member and User: blank

I turned on debug when it didn't work and tried again which generated the error message: "Action 125 :: CB GroupJive is not installed" ?

Error from components/com_comprofiler/plugin/user/plug_cbautoactions/library/Action/GroupjiveAction.php which simply checks for this file:
components/com_comprofiler/plugin/user/plug_cbgroupjive/cbgroupjive.class.php

, which doesn't exist. Perhaps you want component.cbgroupjive.php instead?

Ensure CB GroupJive is up to date and within CB > Plugin Management ensure it's Public and Published.

The plugin wasn't public, so that fixed the Auto Action and it works now.  However, I upgraded just the GroupJive and AutoActions components, and now I see I can no longer update users in the backend. It fails with no error message , even if debugging set, and redirects to the Joomla admin dashboard.   I also see it empties the First Name field, front or back, when I try to edit the user.

Update: bizarre. several rounds of cache clearing and checking all fields, and it's now working on the front end,but still the backend is broken. Does not save user changes.

and redirects to the Joomla admin dashboard

Do you have any auto actions acting on user save? You maybe accidently redirecting backend save. Try unpublishing CB Auto Actions and see if that fixes your issue. Alternatively could be something breaking the form HTML. Do you have any Custom HTML fields? If so try unpublishing them and retrying.

I also see it empties the First Name field, front or back, when I try to edit the user.

This sounds like you've some sort of browser autofill being applied. We already set autocomplete="off", but browser extensions like LastPass for example ignore it.