Reference tool
Common Error Code Reference
Look up common HTTP status codes and Windows system error codes, what each one means, and the most likely fixes, a fast troubleshooting reference.
Common Error Code Reference
Showing 43 of 43 entries. Click any row for fix details
Frequently asked questions
What is the difference between a 401 and a 403 HTTP error?
A 401 Unauthorized means the server requires authentication and the request did not include valid credentials, you need to log in. A 403 Forbidden means the server recognized your credentials but you do not have permission to access the requested resource. In practice: 401 means 'who are you?' and 403 means 'I know who you are, but you cannot be here.' If you encounter a 403, check role assignments and permissions with your administrator.
Why do I see a 502 Bad Gateway error and how do I fix it?
A 502 Bad Gateway means the server acting as a proxy or load balancer received an invalid response from an upstream server. Common causes include a crashed application server behind the load balancer, a misconfigured reverse proxy (Nginx, Cloudflare, Azure Front Door), or a deployment in progress. For end users: wait a few minutes and retry, 502s from cloud services are often transient. For operators: check the upstream application server health, review proxy timeout settings, and inspect error logs for the upstream service.
Want this handled for you?
Elevate manages IT & security for regulated firms.
Related reference tools
Network Troubleshooting Guide
A guided, step-by-step flow to diagnose common network problems: no connectivity, slow speeds, DNS, and Wi-Fi, and find the likely cause.
Network Port Reference
Look up common TCP and UDP ports and the services that use them, a fast reference for writing firewall rules and troubleshooting connections.
WiFi Standards Reference
Compare Wi-Fi 4, 5, 6, 6E, and 7 side by side: maximum speeds, frequency bands, channel widths, and the real-world use cases for each.