apo_it
CDCloudflare Developers
•Created by apo_it on 2/27/2025 in #general-help
Weird intermittent HTTP 526 Error, different subdomain is requested
On my webserver I occasionally (about 1 in 20 requests) get an HTTP Error 526 that I can't figure out. If I request the same URL in a browser, about 1 in 20 requests will return an error 526. I checked the SSL config with various tools and it seems fine (also works the majority of times).
I then enabled the SSL debug in apache2 and found that the requests that fail do so, because for some reason it requests a different subdomain which on this server there is no SSL certificate installed. So all the requests (sub1.mydomain.com) work fine but although I request the exact same URL suddenly I can see another subdomain is requested (sub2.mydomain.com) which I also own and operate but on a different server. Since this server can't provide an SSL certificate for that subdomain, the request fails and I get an error 526. I have no idea what happens here and how to debug this error. To me right now the only explanation is, that the Cloudflare cashing somehow messes with the subdomains and requests... Can anybody help?
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