CD
Cloudflare Developers•3d ago
Kitsune

Workers Outbound API Call: Error 525

Hi there! I'm currrently writing a small worker in Rust that needs to issue a call to an API - something trivial (and that works well on my machine). However, when deployed to workers, it seems to result in an "error code: 525" response to the external API Request! These are the request contents themselves: 
Response { status: 525, headers: {\"cache-control\": \"private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0\", \"cf-ray\": \"98761fa430af4a5f-EWR\", \"connection\": \"keep-alive\", \"content-length\": \"15\", \"content-type\": \"text/plain; charset=UTF-8\", \"date\": \"Tue, 30 Sep 2025 19:28:29 GMT\", \"expires\": \"Thu, 01 Jan 1970 00:00:01 GMT\", \"referrer-policy\": \"same-origin\", \"server\": \"cloudflare\", \"x-frame-options\": \"SAMEORIGIN\"} }\n
Response { status: 525, headers: {\"cache-control\": \"private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0\", \"cf-ray\": \"98761fa430af4a5f-EWR\", \"connection\": \"keep-alive\", \"content-length\": \"15\", \"content-type\": \"text/plain; charset=UTF-8\", \"date\": \"Tue, 30 Sep 2025 19:28:29 GMT\", \"expires\": \"Thu, 01 Jan 1970 00:00:01 GMT\", \"referrer-policy\": \"same-origin\", \"server\": \"cloudflare\", \"x-frame-options\": \"SAMEORIGIN\"} }\n
The server to which the request is made has properly configured Let's Encrypt Certificates, thanks to Kubernetes and Cert-Manager, and does not use cloudflare proxy (it's a DNS-only record). Any idea what could be wrong here?
2 Replies
Kitsune
KitsuneOP•3d ago
SSL Info from Curl: 
Server certificate:
*  subject: CN=[REDACTED]
*  start date: Sep 11 13:46:46 2025 GMT
*  expire date: Dec 10 13:46:45 2025 GMT
*  subjectAltName: host "[REDACTED]" matched cert's "[REDACTED]"
*  issuer: C=US; O=Let's Encrypt; CN=R12
*  SSL certificate verify ok.
*   Certificate level 0: Public key type RSA (2048/112 Bits/secBits), signed using sha256WithRSAEncryption
*   Certificate level 1: Public key type RSA (2048/112 Bits/secBits), signed using sha256WithRSAEncryption
*   Certificate level 2: Public key type RSA (4096/152 Bits/secBits), signed using sha256WithRSAEncryption
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
Server certificate:
*  subject: CN=[REDACTED]
*  start date: Sep 11 13:46:46 2025 GMT
*  expire date: Dec 10 13:46:45 2025 GMT
*  subjectAltName: host "[REDACTED]" matched cert's "[REDACTED]"
*  issuer: C=US; O=Let's Encrypt; CN=R12
*  SSL certificate verify ok.
*   Certificate level 0: Public key type RSA (2048/112 Bits/secBits), signed using sha256WithRSAEncryption
*   Certificate level 1: Public key type RSA (2048/112 Bits/secBits), signed using sha256WithRSAEncryption
*   Certificate level 2: Public key type RSA (4096/152 Bits/secBits), signed using sha256WithRSAEncryption
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
Gab
Gab•2d ago
I'm not exactly sure what might be causing the issue, but since I've had some problems with Cloudflare certificates before, it might be worth checking the certificate configuration to see if everything is set up correctly

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