Skip to content
RU Sign In
RU
← All Status Codes
502
Server Error

HTTP status code 502 Bad Gateway

HTTP 502 Bad Gateway is the status code a proxy, load balancer or CDN returns when the upstream server behind it refused the connection or sent a response it could not use.

Fixing this error on a site, a server or an API? Step-by-step guide: HTTP 502 Bad Gateway: What It Means and How to Fix →

Definition (RFC 9110)

HTTP status code 502 Bad Gateway is defined in RFC 9110 (HTTP Semantics), Section 15.6.3 — the current authoritative specification for HTTP semantics, published June 2022, which obsoletes the older RFC 7231 and RFC 2616.

Description

The 502 Bad Gateway status code indicates that the server, while acting as a gateway or proxy, received an invalid response from an inbound server it accessed while attempting to fulfill the request.

Common Causes

  • Upstream server is down
  • PHP-FPM/application process crashed
  • Timeout from upstream server
  • Firewall blocking upstream connection
  • DNS resolution failure for upstream

How to Fix

  • Check upstream server status
  • Restart PHP-FPM or application process
  • Increase proxy timeout values
  • Check nginx/Apache proxy configuration
  • Verify upstream server health

Check your website's HTTP status code

Check now →

Related Status Codes

500
500 Internal Server Error
HTTP 500 Internal Server Error is the generic status code a server returns when a failure on its own side, such as an application exception or a broken configuration, stops it from completing a request. The cause is in the server logs, not in the request.
 501
501 Not Implemented
The server does not support the functionality required to fulfill the request.
 503
503 Service Unavailable
HTTP 503 Service Unavailable is the status code for a temporary outage: the server is overloaded or down for maintenance and asks clients to come back later, optionally with a Retry-After header.
 504
504 Gateway Timeout
HTTP 504 Gateway Timeout is the status code a proxy, load balancer or CDN returns when the upstream server behind it did not answer in time.
 505
505 HTTP Version Not Supported
The server does not support the HTTP protocol version used in the request.
 507
507 Insufficient Storage
The server cannot store the representation needed to complete the request (WebDAV).

Related guides

Longer-form reading on this topic from the knowledge base.

Automate this check

Set up continuous monitoring and get an alert when something breaks. No manual runs to remember.

Start free

Start monitoring for free

Sign up and get access to API, monitoring and notifications

Create Account API Documentation