CiviCRM: WordPress V5.6.2, hosted on CiviHosting

We can successfully send outbound SMS messages but cannot receive replies back through the webhook in Twilio. We either get HTTP 404 Not Found, 502 Bad Gateway (both encountered on version 5.X), or Schema Validation required responses (encountered on version 4.7).

Twilio Error example: enter image description here

We followed the CiviCRM setup documentation here, including using the example callback URL.

I have noticed other posts on Stack Exchange highlighting similar issues with different suggestions for callback URLs but all of those different URL configurations have failed, and none of the posts seem to define a clear answer/solution.

1 Answer 1


The problem may have had to do with SSL certificates. Callback was using a HTTPS POST callback URL but no SSL certificate was in place. After switching the callback URL to HTTP POST, we are now receiving inbound texts. We are still getting Schema Validation Required responses. Will post again if having an SSL cert makes those go away.

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