Thanks for the details — exit code 128 from git almost always points to an authentication or URL/config issue. A couple of quick clarifying questions to make sure we’re on the right path: - Which Prefect version are you using? (I’ll assume 3.x unless you say otherwise.) - What are your import statements for

GitRepository

and

GitHubCredentials

? (In Prefect 3.x, the typical path is to use the

git_clone

pull step with

prefect_github.GitHubCredentials

rather than a

GitRepository

class.) Why this is happening - The

gh

CLI login you tested is separate from

git clone

authentication. Unless your git is configured to use

gh auth git-credential

, a non-interactive

git clone

will not pick up

gh

auth. This is why

gh

can succeed but

git clone

(which Prefect uses under the hood) can fail with 128. - In Prefect 3.x, the recommended path is to either: - Use

Flow.from_source(...).deploy(...)

and configure pull steps for cloning, or - Call the

git_clone

pull step directly with an access token or a

GitHubCredentials

block. Fastest way to verify your token and URL on the same machine/container where the script runs - Run this quick Python test to isolate the issue:

import os
from prefect.deployments.steps.pull import git_clone
from prefect_github import GitHubCredentials

# Make sure BC_ACCESS_TOKEN is set in THIS environment
token = os.environ.get("BC_ACCESS_TOKEN")
assert token, "BC_ACCESS_TOKEN not set in this environment"

git_clone(
    repository="<https://github.com/OWNER/REPO.git>",  # must be the full HTTPS URL
    branch="main",
    credentials=GitHubCredentials(token=token),
)

If this fails with 128, the error text in stderr usually clarifies whether it’s “authentication failed” or “repository not found”. Common fixes for exit code 128 in this context - URL must be HTTPS and include .git:

<https://github.com/owner/repo.git>

- Token scope/authorization: - For a classic PAT: ensure it has

repo

scope for private repos. - For a fine-grained PAT: ensure the token is granted access to the specific repo with at least “Contents: Read”. - If your org enforces SSO, make sure the token is SSO-authorized for that org. - Environment mismatch: ensure

BC_ACCESS_TOKEN

is set in the environment where the Prefect worker/process runs (containers often miss local env vars). - Don’t rely on

gh

auth unless you’ve configured git to use it: - You’d need

git config --global credential.helper '!gh auth git-credential'

for git to reuse

gh

auth. Otherwise, pass the token explicitly as shown above. - Submodules: if your repo has submodules and you set

include_submodules=True

, ensure those submodules also use HTTPS and are accessible with the same token. Recommended Prefect 3.x patterns - Programmatic pull (good for quick testing or ad hoc runs):

from prefect.deployments.steps.pull import git_clone
from prefect_github import GitHubCredentials

git_clone(
    repository="<https://github.com/OWNER/REPO.git>",
    branch="main",
    credentials=GitHubCredentials(token=os.environ["BC_ACCESS_TOKEN"]),
)

- Deploy from source (recommended for deployments): - Use

Flow.from_source("<https://github.com/OWNER/REPO>", entrypoint="path/to/flow.py:my_flow")

then

deploy(...)

. - Provide credentials via your project’s pull step config (in

prefect.yaml

) using the same

git_clone

step and

GitHubCredentials

block. - Docs: - prefect-github integration - git pull steps API - prefect.yaml (deployments) If you can share: - Your Prefect version - Your imports for `GitRepository`/`GitHubCredentials` - The full stderr from the 128 failure (or run the short

git_clone

snippet above and paste the error) …I can pinpoint the exact fix.