CI Troubleshooting Quick Reference

Common CI failure patterns and how to diagnose them from the logs.

Reading CI Logs

# With gh
gh run view <RUN_ID> --log-failed

# With curl — download and extract
curl -sL -H "Authorization: token $GITHUB_TOKEN" \
  https://api.github.com/repos/$GH_OWNER/$GH_REPO/actions/runs/<RUN_ID>/logs \
  -o /tmp/ci-logs.zip && unzip -o /tmp/ci-logs.zip -d /tmp/ci-logs

Common Failure Patterns

Test Failures

Signatures in logs:

FAILED tests/test_foo.py::test_bar - AssertionError
E       assert 42 == 43
ERROR tests/test_foo.py - ModuleNotFoundError

Diagnosis:

1. Find the test file and line number from the traceback
2. Use read_file to read the failing test
3. Check if it's a logic error in the code or a stale test assertion
4. Look for ModuleNotFoundError — usually a missing dependency in CI

Common fixes:

• Update assertion to match new expected behavior
• Add missing dependency to requirements.txt / pyproject.toml
• Fix flaky test (add retry, mock external service, fix race condition)

Lint / Formatting Failures

Signatures in logs:

src/auth.py:45:1: E302 expected 2 blank lines, got 1
src/models.py:12:80: E501 line too long (95 > 88 characters)
error: would reformat src/utils.py

Diagnosis:

1. Read the specific file:line numbers mentioned
2. Check which linter is complaining (flake8, ruff, black, isort, mypy)

Common fixes:

• Run the formatter locally: black ., isort ., ruff check --fix .
• Fix the specific style violation by editing the file
• If using patch, make sure to match existing indentation style

Type Check Failures (mypy / pyright)

Signatures in logs:

src/api.py:23: error: Argument 1 to "process" has incompatible type "str"; expected "int"
src/models.py:45: error: Missing return statement

Diagnosis:

1. Read the file at the mentioned line
2. Check the function signature and what's being passed

Common fixes:

• Add type cast or conversion
• Fix the function signature
• Add # type: ignore comment as last resort (with explanation)

Build / Compilation Failures

Signatures in logs:

ModuleNotFoundError: No module named 'some_package'
ERROR: Could not find a version that satisfies the requirement foo==1.2.3
npm ERR! Could not resolve dependency

Diagnosis:

1. Check requirements.txt / package.json for the missing or incompatible dependency
2. Compare local vs CI Python/Node version

Common fixes:

• Add missing dependency to requirements file
• Pin compatible version
• Update lockfile (pip freeze, npm install)

Permission / Auth Failures

Signatures in logs:

fatal: could not read Username for 'https://github.com': No such device or address
Error: Resource not accessible by integration
403 Forbidden

Diagnosis:

1. Check if the workflow needs special permissions (token scopes)
2. Check if secrets are configured (missing GITHUB_TOKEN or custom secrets)

Common fixes:

• Add permissions: block to workflow YAML
• Verify secrets exist: gh secret list or check repo settings
• For fork PRs: some secrets aren't available by design

Timeout Failures

Signatures in logs:

Error: The operation was canceled.
The job running on runner ... has exceeded the maximum execution time

Diagnosis:

1. Check which step timed out
2. Look for infinite loops, hung processes, or slow network calls

Common fixes:

• Add timeout to the specific step: timeout-minutes: 10
• Fix the underlying performance issue
• Split into parallel jobs

Docker / Container Failures

Signatures in logs:

docker: Error response from daemon
failed to solve: ... not found
COPY failed: file not found in build context

Diagnosis:

1. Check Dockerfile for the failing step
2. Verify the referenced files exist in the repo

Common fixes:

• Fix path in COPY/ADD command
• Update base image tag
• Add missing file to .dockerignore exclusion or remove from it

Auto-Fix Decision Tree

CI Failed
├── Test failure
│   ├── Assertion mismatch → update test or fix logic
│   └── Import/module error → add dependency
├── Lint failure → run formatter, fix style
├── Type error → fix types
├── Build failure
│   ├── Missing dep → add to requirements
│   └── Version conflict → update pins
├── Permission error → update workflow permissions (needs user)
└── Timeout → investigate perf (may need user input)

Re-running After Fix

git add <fixed_files> && git commit -m "fix: resolve CI failure" && git push

# Then monitor
gh pr checks --watch 2>/dev/null || \
  echo "Poll with: curl -s -H 'Authorization: token ...' https://api.github.com/repos/.../commits/$(git rev-parse HEAD)/status"