❌ Error: No module named 'prefect_aws.ecs'

That 500 is coming from your local Docker daemon (http+docker://localnpipe is the Windows named pipe), not from Prefect or ECS. Prefect is asking Docker to build/tag/push an image and Docker is crashing on an images endpoint. The usual culprits: - Not logged into ECR from your local Docker session - Invalid image reference (e.g., uppercase letters or bad format) - ECR repository doesn’t exist - Docker Desktop hiccup on Windows Quick checks and fixes 1) Validate the image name - Make sure it’s fully lowercase and in ECR form: ACCOUNT_ID.dkr.ecr.REGION.amazonaws.com/repo:tag - No uppercase anywhere in the repository name or registry; tag should also be valid. 2) Log in to ECR from the shell you run deploy in

aws ecr get-login-password --region <REGION> | docker login --username AWS --password-stdin <ACCOUNT_ID>.dkr.ecr.<REGION>.<http://amazonaws.com|amazonaws.com>

3) Ensure the repo exists

aws ecr describe-repositories --repository-names <repo> --region <REGION> || \
aws ecr create-repository --repository-name <repo> --region <REGION>

4) Reproduce outside Prefect to isolate Docker - From your project directory:

docker build -t <ACCOUNT_ID>.dkr.ecr.<REGION>.<http://amazonaws.com/<repo>:<tag|amazonaws.com/<repo>:<tag>> .
docker push <ACCOUNT_ID>.dkr.ecr.<REGION>.<http://amazonaws.com/<repo>:<tag|amazonaws.com/<repo>:<tag>>

- If this fails, it’s definitely Docker/ECR auth/naming and not Prefect. The CLI will often give a clearer message than the SDK’s “500”. 5) If you don’t want Prefect to build/push on every deployment - Use a prebuilt image and disable build/push during

prefect deploy

. In Prefect 3.x, deployments accept

image

,

build

, and

push

flags. With a prebuilt image in ECR: - In prefect.yaml:

deployments:
  - name: my-deployment
    entrypoint: path/to/flow.py:my_flow
    work_pool: my-ecs-pool
    image: <ACCOUNT_ID>.dkr.ecr.<REGION>.<http://amazonaws.com/<repo>:<tag|amazonaws.com/<repo>:<tag>>
    build: false
    push: false

- Or with the Python API:

from prefect.deployments import deploy

deploy(
    work_pool_name="my-ecs-pool",
    image="<ACCOUNT_ID>.dkr.ecr.<REGION>.<http://amazonaws.com/<repo>:<tag|amazonaws.com/<repo>:<tag>>",
    build=False,
    push=False,
)

Then manage image builds/pushes in CI and keep deployments fast and boring. 6) Windows-specific sanity checks - Ensure Docker Desktop is running and accessible from your shell. - If you’re using WSL2, verify Docker is using the WSL2 backend and your project files are accessible. - If the error persists, try restarting Docker Desktop; the daemon occasionally throws a 500 when its registry auth cache gets into a mood. Useful docs - Prefect 3: Docker image builds and usage - Prefect 3: ECS guide If you can share: - Your OS (I’m guessing Windows from localnpipe), Docker Desktop version - The exact image name you’re using - Whether you can

docker push

the image manually - The part of your prefect.yaml (or command) that sets image/build/push …I can pinpoint this faster than a depressed robot can find the meaning of life.