Sorry, the Login ID, Client Key, or both, are incorrect.

And you were using the plugin successfully before? Are regular payments made by customers going through to Authorize.Net?

Yes and Yes

Have you checked to make sure Sandbox Mode is disabled? Note that you will need to refresh the Edit Order screen after you make any changes to the settings.

Yep, no settings have changed. It just started not working. Where can i get debug logs to send over to you?

There are no debug logs. Were any plugins updated right before this issue started? Were any changes made to the server? It’s strange that the issue just started happening suddenly.

That error is shown when Authorize.net returns E00007 on the client-side via Accept.js:
https://developer.authorize.net/api/reference/responseCodes.html#search=E00007&start=1

E00007 from Accept.js can be caused by an incorrect API Login ID or Public Client Key, or by sending a request to the wrong API endpoint (production or sandbox). As far as I can tell, nothing else causes that error (the Transaction Key is not used client-side).

Are you familiar with the browser devtools? Using the Network tab, you can verify that the correct Login ID and Client Key are being submitted to the correct URL. If you need instructions on how to do that, let me know what browser you use and I’ll write it up.

Did you end up figuring it out?

I’m having the same problem, but with a new installation. I’ve got it set to sandbox, I used the same Login ID, Transaction Key and Signature Key as is currently working for public site orders in sandbox mode. I tried disabling all non-essential plugins. Everything is up to date, I’m using the Divi theme.

@sammcc – This plugin actually doesn’t use the Signature Key. Can you make sure you’ve set the correct Public Client Key? You can find instructions here.