GitHub Actions Private Submodule Checkout Failure — Permission Denied

What this error means

Permission denied (publickey). fatal: Could not read from remote repository is a GitHub Actions failure pattern reported for developers trying to github actions workflow 中拉取私有子模块时认证失败，ci/cd 流程被阻断，需要配置正确的 token/ssh key. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Source: r/devops and r/node threads — multiple reports of GitHub Actions failing to checkout private submodules due to SSH publickey authentication. Classic CI/CD blocker for teams using monorepos with private dependencies. Distinct from covered ‘permission denied publickey’ as specifically about submodule checkout context.

Common causes

• Source: r/devops and r/node threads — multiple reports of GitHub Actions failing to checkout private submodules due to SSH publickey authentication. Classic CI/CD blocker for teams using monorepos with private dependencies. Distinct from covered ‘permission denied publickey’ as specifically about submodule checkout context.

Quick fixes

1. Confirm the exact error signature matches Permission denied (publickey). fatal: Could not read from remote repository.
2. Check the GitHub Actions account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://www.reddit.com/r/devops/comments/18gy2p2/github_action_fails_to_checkout_private_submodule/
• https://www.reddit.com/r/node/comments/ratznx/github_actions_error_while_pushing_code_to/

Evidence note: Source: r/devops and r/node threads — multiple reports of GitHub Actions failing to checkout private submodules due to SSH publickey authentication. Classic CI/CD blocker for teams using monorepos with private dependencies. Distinct from covered ‘permission denied publickey’ as specifically about submodule checkout context.

Related errors

• GitHub Actions

FAQ

What should I check first?

Start with the exact Permission denied (publickey). fatal: Could not read from remote repository text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed GitHub Actions workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Permission denied (publickey). fatal: Could not read from remote repository.