Unknown error: "HTTPError: 409 Client Error"

[giraffe009]

Dear Community,

I’m encountering a 409 Client Error during Reinforcement Learning (RL) training, which directs me to a specific URL. Upon checking the URL, I receive a response with "message": null.

I’ve included the error messages below for reference.

Has anyone experienced this issue before or can offer insights on how to resolve it?

Best regards,
T Z Oo.

HTTPError: 409 Client Error: Cannot take action; conflict with engine state: not in paused state (reason: UNKNOWN-CHECK LOGS) for url http://127.0.0.1:52593/rl -- check alpyne.log for more info

{"message":null,"state":"PAUSED","time":2880.0,"date":"2025-02-13T16:00:00.000+00:00","progress":9.917355371900827E-4,"stop":false,"observation":{"campaign_length":120,"powerPeak":24.10548,"t1_act":[0.0,25.0,35.0,0.0],"t2_act":[40.0,5.0,0.0,20.0],"t1_manufactured":[0.0,25.0,35.0,0.0],"t2_manufactured":[40.0,0.0,0.0,0.0],"t1_quarantined":[0.0,0.0,2.0,0.0],"t2_quarantined":[2.0,0.0,0.0,0.0],"t1_finishTime":[0.0,36.08950049356548,91.69268894598213,0.0],"t2_finishTime":[38.922168998251806,0.0,0.0,0.0],"t1_coTime":[0.0,41.88609585034389,91.69268894598213,0.0],"t2_coTime":[45.431186134644804,0.0,0.0,0.0],"totalCost":[5257.858552247653,68379.92133754944],"co2":[42676.41007953006,555018.6516445517],"simTime":120.0},"sequence_id":1640,"episode_num":1094,"step_num":0}

[SiavashMoghaddam]

Hi dear @giraffe009 ,
I’ve encountered this 409 error “conflict with engine state” for a couple of reasons:

1. HTTP server startup failure
   • Right after launching the Python client, the embedded HTTP server in the simulator may not be fully initialized.
   • Retrying the initialization (or re-instantiating the simulation client 1–3 times) often resolves the issue.
2. Stop-condition already triggered on the AnyLogic side
   • If you set a stop condition in the AnyLogic model before exporting, the simulator can immediately enter PAUSED (or TERMINATED) as soon as you call step().
   • Any subsequent POSTs to /rl then return a 409 because the engine isn’t in a RUNNING state.

To help pinpoint exactly what’s happening in your case, could you share a minimal snippet?