SMTP: emails fail or never arrive
How to check: use “Send test email” under Communications → Email Settings, then check Communications → Email Log for the exact error.
Common causes: wrong port/encryption combination, an app-specific password required by your mail provider instead of your normal account password, or your host blocking outbound SMTP on the standard port.
SMS: test message fails
How to check: use “Send test SMS” under Communications → SMS Settings — the error message returned is your provider’s own response, not a generic failure.
Common causes: wrong authentication method selected for your provider, an expired API key, or an incorrect sender ID format.
Google reCAPTCHA errors
How to check: confirm the site key and secret key are both entered and belong to the same reCAPTCHA site registration, and that your domain is registered with Google for that key pair.
Common cause: a site key from a different domain, or a v2/v3 mismatch between what’s configured and what Google issued.
Payment failures
How to check: confirm you’ve entered live (not sandbox/test) credentials if you’re accepting real payments, and that the provider is enabled under Platform → Payment Settings.
Common cause: test-mode credentials left in place after launch.
Uploads failing
How to check: the error message states whether the file exceeds the configured limit or was rejected for its type — see Media Library.
Common cause: a file larger than either the application’s configured limit or your server’s own PHP upload ceiling, whichever is smaller.
Google sign-in errors
How to check: confirm the redirect URI registered in your Google Cloud project exactly matches your site’s actual login callback URL, including https:// and no trailing slash mismatch.
Common cause: a redirect URI mismatch — Google will state this explicitly in its own error page.