Errors and Response Codes

General Tips

  • make sure the load tested URL is up and publicly available before running any load or performance tests
  • check the HTTP method (GET is the request done by browsers when accessing a website or an API endpoint)
  • start with a small number of clients and check the number of errors
  • try to increase the number of the clients gradually to understand how your API, Website or WebApp behaves
  • check the Time, Latency, Hits, Throughput and Errors for each test to check the performances of your system

3xx response codes (redirection)

  • if the URL added for the load test is doing any redirects to another URL
  • if you are testing the redirection, try to do the load test on the final URL, after the redirects end
  • clear the "Follow redirects" checkbox next to the URL (it is checked by default) if you want to avoid redirecting your requests and do the load test on the URL added

4xx response codes (client side errors)

  • the URL is correct and publicly available
  • check the HTTP Method used: GET, POST, PUT or DELETE (GET is the request done by browsers when accessing a website or an API endpoint)
  • the request headers, cookies, query params or basic HTTP auth params are set correctly
  • for what each 4xx code means, see Common HTTP Error status codes; to see which codes your run returned, open the Errors tab (Errors by Type and Error Rate)

5xx response codes (server side errors)

  • the response code, usually if the load tested API, WebSite, Web or Mobile Application does not handle the load properly you will start receiving 503 Service Unavailable responses.
  • try to reduce the number of clients (concurrent users) for your load test and check the boundaries of your system

For more information about how to load test your websites and APIs in the cloud with LoadFocus Load Testing tool, see Load Testing Service or JMeter Load Testing Service.

Response Codes (Full list)

Based on w3schools.com and RFC 9110, here are the HTTP status codes you can see in the results of a load test for API endpoints, websites, and web and mobile applications:

1xx: Information

  • 100 Continue The server has received the request headers, and the client should proceed to send the request body
  • 101 Switching Protocols The requester has asked the server to switch protocols
  • 103 Early Hints The server sends preliminary headers so the client can start loading resources before the final response

2xx: Successful

  • 200 OK The request is OK (this is the standard response for successful HTTP requests)
  • 201 Created The request has been fulfilled, and a new resource is created
  • 202 Accepted The request has been accepted for processing, but the processing has not been completed
  • 203 Non-Authoritative Information The request has been successfully processed, but is returning information that may be from another source
  • 204 No Content The request has been successfully processed, but is not returning any content
  • 205 Reset Content The request has been successfully processed, but is not returning any content, and requires that the requester reset the document view
  • 206 Partial Content The server is delivering only part of the resource due to a range header sent by the client

3xx: Redirection

  • 300 Multiple Choices The request has more than one possible response and the client can choose one
  • 301 Moved Permanently The requested page has moved to a new URL
  • 302 Found The requested page has moved temporarily to a new URL
  • 303 See Other The requested page can be found under a different URL
  • 304 Not Modified Indicates the requested page has not been modified since last requested
  • 306 (Unused) Reserved, no longer used
  • 307 Temporary Redirect The requested page has moved temporarily to a new URL
  • 308 Permanent Redirect The requested page has moved permanently to a new URL and the client must repeat the request with the same method

4xx and 5xx: Client and Server Errors

See Common HTTP Error status codes for the meaning of each 4xx and 5xx code.

Other: Connection Error

The URL added for the load test could not be accessed for one of the following reasons:

  • the URL is not publicly accessible (we support only URLs which can be accessed publicly via Internet)
  • the system crashed for some reason
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