Troubleshooting
A thread group is missing from my results
The usual cause is a data file path that can't be resolved. Every thread in that group fails before sending a request, so there are no errors to report — the group simply isn't there.
Check the CSV Data Set Config entries in that thread group and make each one a relative path (./data.csv), then confirm the file is uploaded. See Test Plan Requirements.
The test finished in seconds with no results
Usually the plan didn't start properly. Check:
- The plan runs locally:
jmeter -n -t plan.jmx - Every referenced file is uploaded
- The machine is big enough — an undersized generator can fail to start JMeter at all rather than running slowly
Max Users is lower than I expected
Max Users adds up the concurrent users reported by every machine. If you ran on 5 generators and it shows roughly one machine's worth, the others weren't producing load.
Check the Fleet page: were all the machines connected? Open Watch during a run to see per-machine activity live.
A machine shows as on, but not connected
The machine is running but its agent isn't reaching Atlas. On the machine:
- Confirm the Atlas agent service is running
- Confirm it can reach your Atlas instance over outbound HTTPS
- Check for a proxy or firewall rule blocking outbound connections
The agent reconnects on its own once the connection is restored.
My test is queued and hasn't started
A load generator runs one test at a time. If the machines you asked for are busy, your run waits and starts automatically when they free up. Either wait, or choose different machines.
Stop said it couldn't reach a machine
Atlas only marks a machine stopped once it has confirmed the process actually ended. If it can't reach one, it tells you and the run stays open — deliberately, so a test can't keep running unnoticed while the record says it stopped.
Retry the stop when the machine is reachable again.
Error rate is high but I can't see why
Click the Error % cell for a request in the aggregation report. That opens the actual errors — response codes, messages, and the full request and response for each distinct failure.
If errors are concentrated in one endpoint, click its Label to chart that request on its own and see when it started failing.
Results look wrong for one request
Check whether the same sampler name exists in more than one thread group. Atlas keeps them as separate rows attributed to the right group — if you expected them combined, that's why the numbers differ from a single-machine JMeter run.
A recorded plan fails on the second run
Usually a dynamic value that wasn't correlated — a token that was valid when you recorded and isn't now. Re-record with correlation enabled (the default), and check that the step which issues the token is part of the recording.
Getting help
When reporting a problem, include the test ID (SHOP-20260818-194201). It identifies the run and everything recorded about it.