How to Fix Nginx WebSockets "Connection: Upgrade" Header Dropped Behind Load Balancer
WebSocket connections work fine when testing directly against Nginx, but fail once a load balancer (ALB, ELB, or another reverse proxy) sits in front of it....
Category
Nginx
Fixes for reverse proxy errors, SSL configuration, and caching issues in Nginx.
How to Fix "Nginx 502 Bad Gateway" Error With PHP-FPM or Node.js
Nginx returns a 502 error page instead of your application's response, which means Nginx itself is running fine but couldn't get a valid response from whatever...
How to Resolve "Nginx 413 Request Entity Too Large" Upload Error
A file upload that should work fails immediately with a 413 status instead of reaching your application code at all. Nginx rejects request bodies larger than...
How to Fix "Nginx 504 Gateway Time-out" on Long Running Requests
A request that takes a while to process — a report generation, a large data export, a slow third-party API call — fails with a 504 instead of eventually...
How to Resolve "nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address Already in Use)"
Nginx refuses to start or reload, reporting that port 80 (or whatever port it's configured for) is already claimed by something else. This means another...
How to Fix "Nginx 403 Forbidden" Error on Static File Hosting
Nginx returns a 403 error for a static file you're sure exists and should be publicly accessible. Unlike a 404, this means Nginx found something at that path...
How to Resolve "Nginx SSL Certificate Error: x509: Certificate Signed by Unknown Authority"
A client connecting to your Nginx server over HTTPS rejects the certificate as untrusted, even though you're confident you installed a valid certificate from a...
How to Fix "Nginx proxy_pass Not Forwarding Custom Headers"
Your backend expects a custom header — an API key, a request ID, an Authorization token — but it never arrives, even though the client is clearly sending it...
How to Resolve "Nginx server_name Wildcard Matching Not Working"
You configure a wildcard server_name expecting it to match any subdomain, but requests to those subdomains aren't landing in the block you expect — either...