Error 520 after server migration

Hi there,

i’m new to Cloudflare i this 520 Error message makes me crazy. A few days ago i had 16 of 20 of my Services configured WITH Cloudflare Proxy. I like the way that Cloudflare handles my SSL Certificate, so i would love to use this feature. The 4 other Services had 520 HTTP Error issues so i decided to publish them without Cloudflare proxy (DNS only) and do letsencrypt. So far so good.

A few days ago, i needed to migrate the most of my services to another Proxmox Server. I changed the Nginx Proxy Manager to adress the new virtual machines and those services are up and running without issues. Only Cloudflares gives me an 520 error. When i deactivate Cloudflare Proxy and do DNS only, the services work fine.

I could handle ignore this issue, let Cloudflare proxy deactivated and use letsencrypt certificates. But i would really love to use Cloudflare as Service here. I already cleaned browser cache and Cloudflare cache. Waited a few days. Switched to developer mode. I dont know WHERE the issue is. Services are up and running, reachable from the network and do not respond with an HTTP Error Code.
There a no log entries in the nginx log.

Maybe someone can help and has experiance with that?

The Services that dont work anymore:

  • Bitwarden
  • 4 own developed Rest API
  • Heimdall Dashboard
  • Funkwhale
  • Paperless-ng
  • MailMonk
  • Mailcow Mailserver (Only the Web UI)
  • Nextcloud
  • 2 Static Webpages (gohugo websites)


Best Regards

Are you saying you do not have a certificate on your server?

No valid certificates from a trusted Authority for the big wide internet. No.
My Web servers are using self-signed certificates from my internal CA and used for “internal security” only.

In that case you have a security issue in the first place and should fix that on the server.

Check out Origin certificates.

Hm ok. I will check this out. Thanks

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