Troubleshooting of HTTP errors
![]() |
HTTP status code
400 Bad Request[edit]
Root cause of 400 Bad Request. HTTP Error 400. The request is badly formed.
- "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)"
Possible solution:
- Modify the request headers
403 Forbidden Error[edit]
See: How to fix the 403 forbidden error
404 File Not Found[edit]
Solution: Check if the accessed link is correct, see "404 Not Found | Possible solutions for pages not found"
405 Method Not Allowed Error[edit]
Solution: Check if the accessed file or resource supports the HTTP protocol being used. For example, if the resource is restricted to POST requests but you're using GET.
414 Request-URI Too Large[edit]
Solution: Change the request protocol to POST instead of GET
415 Unsupported Media Type[edit]
Solution: "Set the Content-Type or Content-Encoding in the request or direct access to the data." For example: When encountering this error with RESTful API, a possible solution is to add to the HTTP Headers:
Content-Type: application/json
429 Too Many Requests[edit]
Root Cause:
- Accessing website resources or web service API too frequently
Solutions:
- Adjust the delay time based on your usage patterns and the service's limits e.g. Increase the delay time between requests (e.g., add a 1-second pause between each request).
- If accessing a web service API, read the documentation to understand the API's rate limits. Check if you can request a higher quota limit from the service provider
- Implement exponential backoff retry mechanism: Detect rate limit errors (HTTP 429) in your application. Increase the delay time with each failed retry (e.g., 2 seconds, 4 seconds, 8 seconds). Continue retrying until the request succeeds or maximum retry count is reached.
502 Bad Gateway[edit]
Cause:
- Error occurs between network devices, users cannot directly handle it.
Solutions:
- Bypass browser cache, refresh the page
- Try reconnecting after a while
Error 1020: Access Denied[edit]
- See link for understanding how to resolve Error 1020 Access Denied to get your website back online
Content-Type: application/json
From HTTP Cats
Related websites:
Other possible root causes[edit]
- CDN (Content delivery network)
Related pages[edit]
References[edit]
Troubleshooting of ...
- PHP, cUrl, Python, selenium, HTTP status code errors
- Database: SQL syntax debug, MySQL errors, MySQLTuner errors or PostgreSQL errors
- HTML/Javascript: Troubleshooting of javascript, XPath
- Software: Mediawiki, Docker, FTP problems, online conference software
- Test connectivity for the web service, Web Ping, Network problem, Web user behavior, Web scrape troubleshooting
Template