Browser – Request Failure

Request Failure Root Cause is exposed when at least one of the transaction spans received response code is of 4xx or 5xx series. There are also some exceptions, we are not considering spans with response code 400, 401, 403, 409, 418, 426, 451 as failed because they are used a lot in REST APIs to describe behaviour of business rules.

These can be totally different reasons why a spans fails, here’s some examples:

  • Requesting some resource (CSS, image) is failed with 404 code because it’s not found
  • Receiving code 502 may indicate that a proxy server the browser is communicating with cannot establish a connection with the backend server processing responses (for example a nginx server in front of a jvm)
  • 500 error code means that the server is failing to produce response and one needs to acquire additional information from backend server logs.