Short answer - It’s safe: this warning just means Prefect checked for matching global concurrency limits and didn’t find any; your tasks will run unthrottled. - You can stop it by either creating the limits (if you want throttling), removing the tags that trigger the check, or suppressing the log with a custom logging config. Why you’re seeing it - In Prefect 3.x, Prefect will attempt to acquire global concurrency limits that match your flow/task run tags (and any explicit concurrency names you acquire in code). - If no matching limit exists, Prefect logs “Concurrency limits ... do not exist – skipping acquisition” and proceeds. Options to remove the warning 1) Create the intended limits (recommended if you do want throttling) - Create a limit for each name shown in the warning and choose a capacity:

prefect global-concurrency-limit create <name> --limit <N>

- Inspect and list limits:

prefect global-concurrency-limit ls
prefect global-concurrency-limit inspect <name>

- Docs: Global concurrency limits and CLI reference: CLI: global-concurrency-limit 2) Remove or change tags if you don’t want tag-based concurrency - If your deployments/tasks add tags and you don’t intend to use concurrency-by-tag, remove those tags to avoid the acquisition attempt. 3) Suppress the log message (if you’re fine running without limits) - Add a custom logging config to raise the level for the concurrency logger. Create a

logging.yml

and point Prefect to it (see docs below). Minimal example:

version: 1
disable_existing_loggers: False

loggers:
  prefect:
    level: INFO
    propagate: True
  prefect.concurrency:
    level: ERROR    # hides the “skipping acquisition” warning
    propagate: True

handlers:
  console:
    class: rich.logging.RichHandler
    level: INFO

root:
  level: INFO
  handlers: [console]

- Docs: Customize logging in Prefect Is it safe to ignore? - Yes—if you are not relying on concurrency limits, this is just noise. Tasks run as before (no throttling). If you do intend to control concurrency, create the limits so Prefect can enforce them. If you can share one full log line (including the names it prints), I can suggest the exact limits to create or confirm which tags are triggering the check.