Why Is an Error Reported When I View the Trace Details?

Symptom: When I click Detail in the error trace column on the Exceptions tab page, an error is reported on the trace page. There is no topology, and the root span in the trace list is marked as fake. Alternatively, neither a topology nor a trace list is displayed.

During metric reporting, if an exception occurs, the trace ID will be recorded in the metric and reported. In this case, the Detail button is available on the UI. Click the Detail button and query the trace details by trace ID. However, if the traces fail to be reported, an error occurs. There are two symptoms:

1. The topology is not displayed, but the trace list is displayed. However, the root trace is filled with fake data.
2. Neither the topology nor the trace list is displayed.

If the child span of the trace is reported but the root span fails to be reported, symptom 1 occurs. If there is no child span or neither the child span nor the root span is reported, symptom 2 occurs.

Solution:

1. Check for exception information in the apm.log file, for example, version incompatibility.

   

2. If the apm.log file does not contain exception information, check whether the problem occurs inevitably. If the problem occurs inevitably, it is usually caused by the client. If the problem does not occur inevitably, the background data may be lost.
3. If the problem occurs inevitably and no exception log about the Agent is generated, the customer's service may clear the threadLocal data after the function interception processing. The following figure shows the Jetty framework. In the handle function, the threadLocal of the entire thread will be cleared at the last step. As a result, the Agent cannot report the root span of the trace.