Skip to content
Website Rescue Rescue

/server-errors/

HTTP and Server Errors Troubleshooting

Decode HTTP status codes and browser connection errors—from 403 and 404 to 500, 502, 503, 504, and ERR_ connection failures.

48 topics · 7 published guides

Common symptoms

  • Specific HTTP status code on one or all pages
  • Browser ERR_ connection messages
  • Gateway timeouts under load
  • Origin down behind a CDN
  • Too many redirects

Start here

  1. 01 Record the exact status code or ERR_ message
  2. 02 Test the origin URL bypassing CDN if possible
  3. 03 Check server and application error logs
  4. 04 Note whether the error is global or path-specific

Most common problems

6 signals
403 Intermediate Server Errors

403 forbidden

Learn what causes “403 forbidden,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

Visitors or admins encounter: 403 forbidden

404 Intermediate Server Errors

404 not found

Learn what causes “404 not found,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

Visitors or admins encounter: 404 not found

500 Intermediate Server Errors

500 internal server error

Learn what causes “500 internal server error,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

Visitors or admins encounter: 500 internal server error

502 Intermediate Server Errors

502 bad gateway

Learn what causes “502 bad gateway,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

Visitors or admins encounter: 502 bad gateway

503 Intermediate Server Errors

503 service unavailable

Learn what causes “503 service unavailable,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

Visitors or admins encounter: 503 service unavailable

504 Intermediate Server Errors

504 gateway timeout

Learn what causes “504 gateway timeout,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

Visitors or admins encounter: 504 gateway timeout

All problems in this category

Showing 48 topics · 7 published guides

  • 403P1 · intermediate

    403 forbidden

    Learn what causes “403 forbidden,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • 404P1 · intermediate

    404 not found

    Learn what causes “404 not found,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • 500P1 · intermediate

    500 internal server error

    Learn what causes “500 internal server error,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • 502P1 · intermediate

    502 bad gateway

    Learn what causes “502 bad gateway,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • 503P1 · intermediate

    503 service unavailable

    Learn what causes “503 service unavailable,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • 504P1 · intermediate

    504 gateway timeout

    Learn what causes “504 gateway timeout,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • P1 · intermediate

    ERR_TOO_MANY_REDIRECTS

    Learn what causes “ERR_TOO_MANY_REDIRECTS,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

  • 400P2 · intermediate

    400 bad request

    Learn what causes “400 bad request,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 401P2 · intermediate

    401 unauthorized

    Learn what causes “401 unauthorized,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 429P2 · intermediate

    429 too many requests

    Learn what causes “429 too many requests,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 520P2 · intermediate

    520 unknown error

    Learn what causes “520 unknown error,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 521P2 · intermediate

    521 web server is down

    Learn what causes “521 web server is down,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P2 · intermediate

    ERR_CONNECTION_REFUSED

    Learn what causes “ERR_CONNECTION_REFUSED,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P2 · intermediate

    ERR_CONNECTION_TIMED_OUT

    Learn what causes “ERR_CONNECTION_TIMED_OUT,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P2 · intermediate

    ERR_NAME_NOT_RESOLVED

    Learn what causes “ERR_NAME_NOT_RESOLVED,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 405P3 · advanced

    405 method not allowed

    Learn what causes “405 method not allowed,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 406P3 · advanced

    406 not acceptable

    Learn what causes “406 not acceptable,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 408P3 · advanced

    408 request timeout

    Learn what causes “408 request timeout,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 409P3 · advanced

    409 conflict

    Learn what causes “409 conflict,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 410P3 · advanced

    410 gone

    Learn what causes “410 gone,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 413P3 · advanced

    413 request entity too large

    Learn what causes “413 request entity too large,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 414P3 · advanced

    414 URI too long

    Learn what causes “414 URI too long,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 415P3 · advanced

    415 unsupported media type

    Learn what causes “415 unsupported media type,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 422P3 · advanced

    422 unprocessable entity

    Learn what causes “422 unprocessable entity,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 501P3 · advanced

    501 not implemented

    Learn what causes “501 not implemented,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 505P3 · advanced

    505 HTTP version not supported

    Learn what causes “505 HTTP version not supported,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 507P3 · advanced

    507 insufficient storage

    Learn what causes “507 insufficient storage,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 508P3 · advanced

    508 loop detected

    Learn what causes “508 loop detected,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 509P3 · advanced

    509 bandwidth limit exceeded

    Learn what causes “509 bandwidth limit exceeded,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 522P3 · advanced

    522 connection timed out

    Learn what causes “522 connection timed out,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 523P3 · advanced

    523 origin is unreachable

    Learn what causes “523 origin is unreachable,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 524P3 · advanced

    524 a timeout occurred

    Learn what causes “524 a timeout occurred,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 525P3 · advanced

    525 SSL handshake failed

    Learn what causes “525 SSL handshake failed,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 526P3 · advanced

    526 invalid SSL certificate

    Learn what causes “526 invalid SSL certificate,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    bad gateway

    Learn what causes “bad gateway,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    connect failed connection refused

    Learn what causes “connect failed connection refused,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    ERR_CONNECTION_RESET

    Learn what causes “ERR_CONNECTION_RESET,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    ERR_EMPTY_RESPONSE

    Learn what causes “ERR_EMPTY_RESPONSE,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    ERR_HTTP2_PROTOCOL_ERROR

    Learn what causes “ERR_HTTP2_PROTOCOL_ERROR,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    ERR_QUIC_PROTOCOL_ERROR

    Learn what causes “ERR_QUIC_PROTOCOL_ERROR,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    gateway timeout

    Learn what causes “gateway timeout,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    no live upstreams

    Learn what causes “no live upstreams,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    request body too large

    Learn what causes “request body too large,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    request header too large

    Learn what causes “request header too large,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    server unexpectedly closed connection

    Learn what causes “server unexpectedly closed connection,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    service temporarily unavailable

    Learn what causes “service temporarily unavailable,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • P3 · advanced

    upstream timed out

    Learn what causes “upstream timed out,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon
  • 418P4 · beginner

    418 error

    Learn what causes “418 error,” how to recognize symptoms, and safe steps to diagnose and repair the problem.

    Coming soon

Related categories

Frequently asked questions

What is the difference between 502 and 503? +
502 usually means a gateway got an invalid response from upstream. 503 means the service is unavailable or overloaded and may recover when capacity returns.

Repair dispatch

Still Need Help Fixing Your Website?

If you are not comfortable editing website files, changing server settings, repairing a database, or troubleshooting a live website, professional help may prevent additional damage or downtime. We will review the problem before accepting the repair.

  • You will receive a clear explanation of the likely cause.
  • We will tell you if the issue falls outside our repair scope.
  • No additional work will be performed without approval.
  • A backup should be created whenever access and website condition allow it.
Emergency repair Request diagnosis

Do not share passwords through an unencrypted contact form.