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Simulation makes no progress

Symptom​

A running simulation stops making progress — the progress indicator stalls, or no results window appears. In severe cases the run ends with:

Too many events occurred without the clock moving. Please check your diagram to make sure there is not an infinite loop.

Cause​

Either the communication between your browser and the simulation server had a momentary interruption, or the model contains an infinite loop: when a case cycles through activities that take no time to complete, the simulated clock never advances.

Resolution​

  1. Wait a moment, then refresh the browser. If the issue was the connection, the progress updates or the results window appears.

  2. If the run still stalls, look for a loop of zero-duration activities: run the simulation in trace mode and watch where cases circle without the clock moving.

  3. Break the loop — give an activityActivity A named step in a process (e.g. "Approve Invoice"). Each event in an event log records one activity occurrence for one case. in the cycle a real Duration, or add an exit condition to the loop's decision outputs.