Very suddenly, I encounter a "404 - Resource not found error" when trying to add a campaign. Module was working fine as of Friday. Stopped working this weekend. I get the same error when trying to view the campaign list. However, I can view old campaigns that have already been sent.
Here is the entire error I get:
Mailchimp\MailchimpAPIException: 404: Resource Not Found - The requested resource could not be found. in Mailchimp\http\MailchimpGuzzleHttpClient->handleRequest() (line 64 of /code/sites/all/libraries/mailchimp/src/http/MailchimpGuzzleHttpClient.php).
My host is Pantheon, and the problem is present on the dev, test and live sites.
One more thing: I upgraded to 7.57 on my dev site, but the same problem is there.
Active
5.5
Campaign Module