How to Fix Nginx 502 Bad Gateway on AWS ALB / CloudFront Upstream Connection
Nginx returns 502 errors specifically when deployed behind AWS Application Load Balancer or CloudFront, even though the same Nginx configuration works fine...
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How to Fix Nginx Proxying to Next.js App Router Returning Static Assets 404
Your Next.js app works fine in local development, but once deployed behind Nginx, CSS, JS chunks, and other static assets return 404 while the actual pages...
How to Fix Nginx SSL Certificate net::ERR_CERT_COMMON_NAME_INVALID After Certbot Run
The browser rejects your site's certificate with a common name mismatch error, even though you just ran Certbot and it reported success. This means the...
How to Fix Nginx Rate Limiting Throwing 503 Instead of 429 to End Users
You've set up Nginx's rate limiting to protect an endpoint from abuse, and it's working — but rate-limited clients see a 503 Service Unavailable instead of the...
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....
How to Fix PostgreSQL "FATAL: Sorry, Too Many Clients Already" With Serverless Next.js
Your Next.js app deployed on a serverless platform (Vercel, AWS Lambda, Netlify Functions) works fine at first, then starts throwing connection errors under...
How to Fix Postgres Query Slow After Migration to AWS RDS / Aurora
A query that ran fast on your old PostgreSQL setup is noticeably slower after migrating to RDS or Aurora, even though the hardware specs look comparable or...
How to Fix Postgres pg_dump Error: Server Version Mismatch Between Local and Remote
Running pg_dump against a remote database fails with a version mismatch error, even though the connection itself succeeds. PostgreSQL's dump tools are strict...
How to Fix PostgreSQL "SSL Error: Certificate Verify Failed" on Heroku / Supabase
Connecting to a managed PostgreSQL database on Heroku or Supabase fails with a certificate verification error, even though the database is genuinely reachable...