Troubleshooting of HTTP errors: Difference between revisions

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HTTP status code
HTTP status code
{{LanguageSwitcher | content = [[Troubleshooting of HTTP errors | EN]], [[Troubleshooting of HTTP errors in Mandarin | 漢字]] }}


__TOC__
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== 400 Bad Request ==
== Troubleshooting HTTP Status Errors ==
 
=== 400 Bad Request ===
 
Root cause: The request itself is malformed. According to the spec, this means "the server cannot or will not process the request due to something perceived to be a client error" — such as invalid syntax, incorrect request message framing, or deceptive request routing.


Root cause of 400 Bad Request. HTTP Error 400. The request is badly formed.
Possible fix:
* "the server cannot or will not process the request due to something that is perceived to be a client error (for example, malformed request syntax, invalid request message framing, or deceptive request routing)"<ref>[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/400 400 Bad Request - HTTP | MDN]</ref>
* Review and correct the request headers


Possibile solution:
=== 403 Forbidden ===
* Modify the request headers


== 403 Forbidden Error ==
See: [[How to fix the 403 forbidden error]]


[[How to fix the 403 forbidden error]]
=== 404 Not Found ===


== 404 File Not Found ==
Fix: Verify that the URL is correct. For more details, see
[[404 Not Found | 找不到網頁的可能解決方法]]
[[404 Not Found]], possible solutions for pages not found".


== 405 Method Not Allowed Error ==
=== 405 Method Not Allowed ===
解決方法：檢查存取的文件或資源支援呼叫使用的 HTTP protocol <ref>[https://dotblogs.com.tw/cotton/2018/03/01/132336 使用Http Post呼叫api卻收到405 method not allowed | 攻城獅的學習筆記 - 點部落]</ref>，例如限制使用 POST ，卻使用 GET 存取。


== 415 Unsupported Media Type ==
Fix: Confirm that the target resource supports the HTTP method you're using. For example, the endpoint may only accept POST requests while you're sending a GET request.


解決方法：「於請求中設置的 {{kbd | key=Content-Type}} 或 {{kbd | key=Content-Encoding}} 或對資料的直接訪問」。參考資料：[https://developer.mozilla.org/zh-TW/docs/Web/HTTP/Status/415 415 Unsupported Media Type - HTTP | MDN]
=== 414 Request-URI Too Large ===
 
Fix: Switch from GET to POST so the data is sent in the request body instead of the URL.
 
=== 415 Unsupported Media Type ===
 
Fix: Explicitly declare the correct Content-Type or Content-Encoding in the request, or access the data directly. For instance, when calling a RESTful API, this error can often be resolved by adding the following header:


例如：RESTful API 遇到該錯誤，可能解決方式是 HTTP Headers 加入
<pre>
<pre>
Content-Type: application/json
Content-Type: application/json
</pre>
</pre>


== 429 Too Many Requests ==
=== 429 Too Many Requests ===
原因：
* 太頻繁存取網站資源


解決方法：
Root cause:
* 調整存取頻率
* The client is hitting the website or API more frequently than the service allows.
* 如果是存取網路服務 API，請閱讀文件了解 API 本身的存取頻率限制 (Rate Limits)


參考資料
Fixes:
* [https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/429 429 Too Many Requests - HTTP | MDN]
* '''Throttle your requests''': Add or increase a delay between requests based on your usage pattern and the service's limits (e.g., pause 1 second between calls).
* '''Check the API rate limits''': Consult the provider's documentation for limits such as Requests Per Minute (RPM) or Requests Per Day (RPD), and find out whether you can request a higher quota.
* '''Use exponential backoff''': Detect HTTP 429 responses in your
  application, then retry with progressively longer delays (e.g., 2s → 4s → 8s) until the request succeeds or a maximum retry count is reached.


== 502 Bad Gateway ==
=== 502 Bad Gateway ===
原因：
* 因為是網路設備間發生錯誤，使用者並無法直接處理<ref>[https://hostingpill.com/zh-TW/502%E9%8C%AF%E8%AA%A4%E7%9A%84%E7%B6%B2%E9%97%9C/ 什麼是502 Bad Gateway錯誤以及如何解決（輕鬆修復指南）]</ref>。


解決方法：
Cause:
* [https://zh.wikipedia.org/zh-tw/Help:%E7%BB%95%E8%BF%87%E6%B5%8F%E8%A7%88%E5%99%A8%E7%BC%93%E5%AD%98 繞過瀏覽器快取]，瀏覽器重新整理頁面
* A failure between upstream network devices/servers — not something the end user can fix directly.
* 過一陣子再重新連線


參考資料
Fixes:
* [https://developer.mozilla.org/zh-TW/docs/Web/HTTP/Status/502 502 Bad Gateway - HTTP | MDN]
* Hard-refresh the page to bypass the browser cache
* Wait a moment and try again


== Error 1020: Access Denied ==
=== Error 1020: Access Denied ===
* [https://www.affde.com/zh-TW/error-1020-access-denied.html 了解如何解決錯誤 1020 訪問被拒絕以使您的網站重新上線 - Affde營銷]
* See the linked guide on resolving Error 1020 (Access Denied) to restore access to your website.


<pre>
== HTTP Cats or Dogs ==
Content-Type: application/json
</pre>


: https://http.cat/200.jpg
<div style="zoom: 0.4;">
: From [https://http.cat/ HTTP Cats]
https://http.cat/200.jpg
</div>
From [https://http.cat/ HTTP Cats]


Related websites
Related websites:
* [https://httpstatusdogs.com/ HTTP Status Dogs]
* [https://httpstatusdogs.com/ HTTP Status Dogs]
== Other possible root causes ==
* CDN (Content delivery network)
== Mock HTTP status error page tools ==
The testing sites that can return 500 and various other HTTP status codes on demand
* [https://the-internet.herokuapp.com/status_codes The Internet]<ref>[https://stackoverflow.com/questions/24736134/is-there-a-website-that-returns-500-and-other-http-response-codes-for-testing httpresponse - Is there a website that returns 500 (and other) HTTP response codes for testing? - Stack Overflow]</ref>
* [https://httpstatus.io/ httpstatus.io]: A bulk checker for HTTP status codes, headers, and redirects, which also offers mock endpoints, e.g. [https://mock.httpstatus.io/500 500]
* [https://www.postman.com/postman/published-postman-templates/documentation/ae2ja6x/postman-echo Postman Echo]: A request/response testing service with status code endpoints, e.g. [https://postman-echo.com/status/500 500]


== Related pages ==
== Related pages ==


* [[Troubleshooting of curl errors]]
* [[Troubleshooting of curl errors]]
* [[Test connectivity for the web service]]


== References ==
== References ==
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{{Template:Troubleshooting}}
{{Template:Troubleshooting}}


[[Category:Programming]]
[[Category: Web server]] [[Category:Programming]] [[Category:Web scraping]]
 
[[Category:Web scraping]]

Latest revision as of 16:49, 11 June 2026


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HTTP status code

🌐 Switch language: EN, 漢字


Troubleshooting HTTP Status Errors[edit]

400 Bad Request[edit]

Root cause: The request itself is malformed. According to the spec, this means "the server cannot or will not process the request due to something perceived to be a client error" — such as invalid syntax, incorrect request message framing, or deceptive request routing.

Possible fix:

  • Review and correct the request headers

403 Forbidden[edit]

See: How to fix the 403 forbidden error

404 Not Found[edit]

Fix: Verify that the URL is correct. For more details, see 404 Not Found, possible solutions for pages not found".

405 Method Not Allowed[edit]

Fix: Confirm that the target resource supports the HTTP method you're using. For example, the endpoint may only accept POST requests while you're sending a GET request.

414 Request-URI Too Large[edit]

Fix: Switch from GET to POST so the data is sent in the request body instead of the URL.

415 Unsupported Media Type[edit]

Fix: Explicitly declare the correct Content-Type or Content-Encoding in the request, or access the data directly. For instance, when calling a RESTful API, this error can often be resolved by adding the following header: 

Content-Type: application/json

429 Too Many Requests[edit]

Root cause:

  • The client is hitting the website or API more frequently than the service allows.

Fixes:

  • Throttle your requests: Add or increase a delay between requests based on your usage pattern and the service's limits (e.g., pause 1 second between calls).
  • Check the API rate limits: Consult the provider's documentation for limits such as Requests Per Minute (RPM) or Requests Per Day (RPD), and find out whether you can request a higher quota.
  • Use exponential backoff: Detect HTTP 429 responses in your
 application, then retry with progressively longer delays (e.g., 2s → 4s → 8s) until the request succeeds or a maximum retry count is reached.

502 Bad Gateway[edit]

Cause:

  • A failure between upstream network devices/servers — not something the end user can fix directly.

Fixes:

  • Hard-refresh the page to bypass the browser cache
  • Wait a moment and try again

Error 1020: Access Denied[edit]

  • See the linked guide on resolving Error 1020 (Access Denied) to restore access to your website.

HTTP Cats or Dogs[edit]

200.jpg

From HTTP Cats

Related websites:

Other possible root causes[edit]

  • CDN (Content delivery network)

Mock HTTP status error page tools[edit]

The testing sites that can return 500 and various other HTTP status codes on demand

Related pages[edit]

References[edit]

  1. ↑ httpresponse - Is there a website that returns 500 (and other) HTTP response codes for testing? - Stack Overflow


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