When does Dynatrace not detect failed requests?

Dynatrace does not detect failed requests when errors are handled by application code because in such situations, the application itself may either catch exceptions or manage error responses internally. This handling process often results in the application returning a success status to the client, even if an issue has occurred in the backend. By managing errors this way, the application may obscure the true nature of the request's success or failure from monitoring tools like Dynatrace. As a result, these failed requests may not be reported, since the response indicates success according to the application logic, despite potential issues being present that a monitoring tool could typically detect.

In contrast, successful responses or client abort exceptions are not related to internal error handling and are typically detectable by monitoring solutions. HTTP status codes below 300 generally indicate successful responses, so those would not fall under the category of failed requests.