incorrect image tag for auto-generated Dockerfile

[zzstoatzz]

Bug summary

reported by Brain from slack

when using the auto generated dockerfile created by prefect in version 3.1.9:

prefect.utilities.dockerutils.BuildError: failed to resolve reference "[docker.io/prefecthq/prefect:3.1.9-python3.13](http://docker.io/prefecthq/prefect:3.1.9-python3.13)": [docker.io/prefecthq/prefect:3.1.9-python3.13](http://docker.io/prefecthq/prefect:3.1.9-python3.13): not found

indeed this reference doesn't exist on dockerhub

Version info

3.1.9

Additional context

No response

[desertaxle]

Was the tag generated when running Python 3.13?

[broonz]

@desertaxle no, I was running python 3.9 locally

[desertaxle]

Interesting! It seems like Prefect picked up the wrong Python version.

@broonz can you share more info about your local setup? Stuff like if you were running a virtual environment and how you set up that virtual environment would be very helpful in debugging. Also, which deployment method were you using when the Dockerfile was auto-generated?

[broonz]

@desertaxle I'm running prefect in a python 3.9 virtualenv, was running the command: prefect deploy based on a prefect.yaml deployment file with the dockerfile: auto option enabled

[desertaxle]

@broonz if you're still seeing this issue, can you run python --version and which python in your virtual environment to check that your shell is using the expected Python version? Also, what tool did you use to create that virtual environment? Sometimes virtual environments can get a little wonky.