Common Issues

Solutions to frequently encountered Copybara problems.

Quick Reference by Error Message

Error Message	Jump To
`No changes to migrate`	No changes
`Authentication failed`	Auth issues
`Permission denied`	Permissions
`Unknown field`	Config errors
`Missing required field`	Config errors
`Invalid glob pattern`	Glob errors
`GitOrigin-RevId not found`	State issues
`Pattern not found`	Transform errors
`verify_match failed`	Verification
`OutOfMemoryError`	Memory issues
`Branch already exists`	PR issues
`rate limit exceeded`	Rate limiting

”No changes to migrate”

Cause: No new commits since last sync.

Solutions:

Use --ignore-noop to not fail:

java -jar copybara.jar migrate copy.bara.sky export --ignore-noop

Force re-sync:

java -jar copybara.jar migrate copy.bara.sky export --force

Start from specific commit:

java -jar copybara.jar migrate copy.bara.sky export --last-rev abc123

Authentication Failed

Cause: Invalid or missing credentials.

Check credentials:

# Test Git access
git ls-remote https://github.com/org/repo

# Check stored credentials
cat ~/.git-credentials

Fix for HTTPS:

git config --global credential.helper store
echo "https://x-access-token:${TOKEN}@github.com" > ~/.git-credentials

Fix for SSH:

ssh-add ~/.ssh/id_ed25519
ssh -T git@github.com

Permission Denied

Cause: Token lacks required permissions.

For GitHub:

Classic PAT: needs repo scope
Fine-grained: needs Contents (RW), Pull requests (RW)

For PRs:

Verify you have write access to destination repo
Check branch protection rules

Configuration Errors

”Unknown field”

Error: Unknown field 'unknown_field' in core.workflow

Fix: Check spelling, consult documentation for valid fields.

”Missing required field”

Error: Missing required field 'authoring' in core.workflow

Fix: Add the required field:

authoring = authoring.pass_thru("Bot <bot@example.com>"),

“Invalid glob pattern”

Error: Invalid glob pattern: [**

Fix: Ensure patterns are valid:

glob(["**"])  # Correct
glob("[**")   # Invalid

State Issues

Wrong state / duplicate syncs

Cause: GitOrigin-RevId mismatch.

Check current state:

git log --grep="GitOrigin-RevId" -1

Reset state:

java -jar copybara.jar migrate copy.bara.sky export --last-rev <known-good-sha>

Missing GitOrigin-RevId

Cause: Manual commits in destination without marker.

Fix: Use --last-rev to specify starting point.

Transform Errors

”Pattern not found”

Error: Pattern 'old_text' not found

Cause: core.replace pattern doesn’t match anything.

Fix: Verify pattern exists in source files or add error handling.

”verify_match failed”

Error: Pattern 'SECRET' found in files

Cause: verify_no_match = True but pattern was found.

Fix: Remove the sensitive content from source or adjust pattern.

PR Destination Issues

”Branch already exists”

Cause: Previous sync branch wasn’t cleaned up.

Fix: Delete the branch and retry:

git push origin --delete copybara/sync-xyz

“PR already exists”

This is normal - Copybara updates existing PRs.

Performance Issues

Slow initial sync

Cause: Processing entire history.

Fix: Use --last-rev to start from recent commit:

java -jar copybara.jar migrate copy.bara.sky export --last-rev HEAD~100

Memory issues

Cause: Large repository or many files.

Fix: Increase Java heap:

java -Xmx4g -jar copybara.jar migrate copy.bara.sky export

Rate Limiting

Symptoms:

rate limit exceeded
API rate limit exceeded for user
HTTP 429 responses

Cause: Too many API calls to GitHub/GitLab.