Since a few weeks ago our users report random 403 errors while browsing our site. Curiously these errors occurred on routes that don’t have an 403 response implemented.
Last week we shipped some client-side HTTP interceptors to send 403 errors and their payload to Sentry to get to the bottom of this.
This is the response payload clients get on several different routes on our service hosted on Render:
<html>
<head><title>403 Forbidden</title></head>
<body>
<center><h1>403 Forbidden</h1></center>
<hr><center>cloudflare</center>
</body>
</html>
We don’t use the Cloudflare-DNS-proxy on our domains so we can’t really explain what is happening.
Any help would be greatly appreciated.