1. Repository Corruption
Understanding the Issue
The repository becomes unusable, showing errors when running Mercurial commands.
Root Causes
- Interrupted operations (e.g., system crash during commit or pull).
- Corrupt or missing files in the
.hgdirectory. - Storage issues or disk corruption.
Fix
Verify the repository integrity:
hg verify
Recover from repository corruption by rolling back the last transaction:
hg recover
If corruption persists, clone the repository from a healthy copy:
hg clone --pull /path/to/backup new-repo
2. Merge Conflicts
Understanding the Issue
Conflicts occur when merging branches, leading to unresolved changes.
Root Causes
- Conflicting modifications to the same file from different branches.
- Incorrect merge strategy selection.
- Uncommitted local changes interfering with the merge.
Fix
Identify conflicting files:
hg resolve --list
Manually resolve conflicts and mark them as resolved:
hg resolve --mark conflicted-file.txt
Abort the merge if necessary:
hg merge --abort
3. Slow Performance on Large Repositories
Understanding the Issue
Operations such as cloning, pulling, or committing take an unusually long time.
Root Causes
- Large binary files or excessive file history.
- Unoptimized repository structure.
- Network latency affecting remote operations.
Fix
Enable repository compression to optimize performance:
hg debugrebuildstate
Prune unnecessary history using the strip command:
hg strip -r old_revision
Use shallow cloning for large remote repositories:
hg clone --pull --rev tip remote-repo
4. Push/Pull Failing Due to Authentication Issues
Understanding the Issue
Pushing or pulling from a remote repository fails with authentication errors.
Root Causes
- Incorrect credentials stored in
.hgrcor password managers. - SSL/TLS handshake failure.
- Repository access restrictions (permissions or branch protection).
Fix
Verify and update authentication details:
hg paths hg pull --debug
Manually specify authentication credentials:
hg pull https://username:password@repo-url
If SSL issues occur, disable certificate verification temporarily (not recommended for production):
[web] cacerts = /etc/ssl/certs/ca-certificates.crt
5. Extension Compatibility Issues
Understanding the Issue
Mercurial extensions fail to load or cause unexpected behavior.
Root Causes
- Incompatible Mercurial version with the extension.
- Incorrect configuration in
.hgrc. - Conflicts between multiple extensions.
Fix
Check installed Mercurial version and extension compatibility:
hg version hg showconfig extensions
Disable problematic extensions temporarily:
[extensions] histedit = !
Ensure extensions are installed in the correct location:
hg help extensions
Conclusion
Mercurial is a powerful version control system, but troubleshooting repository corruption, merge conflicts, performance issues, authentication failures, and extension compatibility is crucial for smooth development workflows. By following best practices for repository maintenance and configuration management, developers can ensure a stable and efficient Mercurial setup.
FAQs
1. How do I recover a corrupted Mercurial repository?
Use hg recover to restore the last transaction or clone from a backup.
2. How can I resolve merge conflicts in Mercurial?
Use hg resolve --list to identify conflicts and manually fix them.
3. Why is my Mercurial repository slow?
Optimize large repositories by pruning history, enabling compression, and using shallow cloning.
4. How do I fix push/pull authentication errors?
Verify credentials, update repository paths, and check SSL/TLS settings.
5. How do I troubleshoot Mercurial extensions?
Check Mercurial version compatibility, disable extensions selectively, and review .hgrc settings.