The correct command should be:

bash
prefect worker start -p <your-work-pool-name> --limit-concurrent-runs 5

Key differences: 1. We use

prefect worker start

instead of

prefect start

2. The flag is

--limit-concurrent-runs

(not

--max-concurrent-runs

) 3. You need to specify a work pool with

-p

or

--pool

(this is required) For example, if your work pool is named "my-pool", the complete command would be:

bash
prefect worker start -p my-pool --limit-concurrent-runs 5

Could you let me know which work pool you're trying to use, and I can provide the exact command you need?

For your case, you have several options to control concurrency: 1. Global Concurrency Limits (GCL):

bash
prefect gcl create my-limit --slots 5

2. Work Queue Concurrency: You can set concurrency limits on work queues within your work pool through the UI or API. 3. Deployment-level Concurrency: You can set concurrency limits at the deployment level when creating your deployments. The approach you choose depends on your specific needs: - Use Global Concurrency Limits (GCL) if you want to limit concurrent runs across your entire Prefect instance - Use Work Queue concurrency if you want to limit concurrent runs for specific work queues - Use Deployment-level concurrency if you want to limit concurrent runs for specific deployments Could you tell me more about what you're trying to achieve with the concurrency limit? This would help me recommend the most appropriate approach for your use case.

Based on the research and recent issues, here's the current correct way to limit concurrent runs on a worker in Prefect 3.x: For a process pool, you can set the concurrency limit at the work pool level:

bash
prefect work-pool create-concurrency-limit "my-process-pool" 5

Or, if the work pool already exists:

bash
prefect work-pool set-concurrency-limit "my-process-pool" 5

Then start your worker normally:

bash
prefect worker start -p "my-process-pool"

Could you try this approach and let me know if you encounter any specific errors? This would help me provide more targeted assistance. Also, it would be helpful to know: 1. Which Prefect version you're using (you can check with

prefect version

) 2. What specific error messages you're seeing 3. What type of work pool you're using (process, kubernetes, etc.)