Some followup info. After logging into Mailchimp and looking on the API Keys page I see the following in the API Calls history:

"The resource submitted could not be validated. For field-specific details, see the 'errors' array."

In the CMC user plugin I have the mapping field as email_address=email. I couldn't find any documentation on how to find the exact MailChimp field name, nor the default joomla email field name. This is what I've seen others use.

Hey Chris,

Just tested this on our website and it seems to works fine.

Just to confirm - we are talking about the backend, right?

Can you provide me with access to the page where you encounter the issue?

Regards,
Daniel

Hi, I think I have the same problem. When editing or adding users in the backend if I go to the Newsletter tab and check the subscribe box then save the user I get the same error as Chris. The user is created or updated ok but the newsletter sub doesn't work.

I haven't tried it from the frontend as I don't make frontend registration available on this site.
Having created the user if I then go to the CMC Component and create a user with the same email and name then it subscribes them ok but doesn't link to the Joomla user.

In a possibly related issue if I place the module on a page it always shows the "It seems that you have already subscribed to this list. Click here to update your profile." text whether or not you are logged in and whether or not if logged in you are subscribed. Also the Click here to update link does nothing whether or not the logged in user is subscribed.

Maybe I have missed something in the installation but it seems as if the links between users and subscribers are not working?

Joomla 3.8.2 CMC 4.1.0

@RogerCo thanks for the detailed explanation. The last part sound especially strange - "it seems that you have already subscribed" - this text shouldn't be shown to non-registered users, as we first check if the user is logged in or not, then if he is logged in, we check his email to see if he is in the database or not.
Roger can you provide me with ftp, phpmyadmin and backend access to your site?

Regards,
Daniel

Thanks for the reply Daniel. Without having changed anything the "It seems you have already..." message has disappeared from both public and registered views of the module in the front end. I can only think it was some weird css conflict that was not overriding display:none on that block which presumably only should appear after an existing subscriber who is logged in ignores the "You are already subscribed" message at the top of the module and clicks subscribe again. Or if a public user subscribes again with the same email (but that wouldn't apply here as only registered users can subscribe for this site)

It maybe I have misunderstood how the backend add user to list works. If I create use the add group function it correctly links joomla users to mailchimp. So I create a new joomla user group called mailchimp and add all the users I want to subscribe to that and it is ok. Creating a single new user with the Add function doesn't link the subscriber to a joomla user even if the email and name match. Now I know that I can live with it. Equally it doesn't subscribe them, it fails with the error above.

The Add group works, but the Add user doesn't. Delete subscriber works ok. That is ok for me.

Sorry I can't provide you with backend access.

Just a thought - does the backend component and front-end module REQUIRE one of the CMC plugins to be available? I do not have the User-CMC plugin enabled since there is no user registration form on this site.