twpayne/chezmoi · error

%s: unsupported mode %o

Error message

%s: unsupported mode %o

What it means

archiveReaderSystem (internal/chezmoi/archivereadersystem.go:69) errors with "%s: unsupported mode %o" when an archive entry is neither a directory, regular file, nor symlink — i.e. its mode type bits match no supported entry kind.

Source

Thrown at internal/chezmoi/archivereadersystem.go:69

		if name.IsEmpty() {
			return nil
		}
		nameAbsPath := options.RootAbsPath.Join(name)

		s.fileInfos[nameAbsPath] = fileInfo
		switch {
		case fileInfo.IsDir():
			// Do nothing.
		case fileInfo.Mode()&fs.ModeType == 0:
			contents, err := io.ReadAll(r)
			if err != nil {
				return fmt.Errorf("%s: %w", name, err)
			}
			s.contents[nameAbsPath] = contents
		case fileInfo.Mode()&fs.ModeType == fs.ModeSymlink:
			s.linkname[nameAbsPath] = linkname
		default:
			return fmt.Errorf("%s: unsupported mode %o", name, fileInfo.Mode()&fs.ModeType)
		}
		return nil
	}); err != nil {
		return nil, err
	}

	return s, nil
}

// FileInfos returns s's fs.FileInfos.
func (s *ArchiveReaderSystem) FileInfos() map[AbsPath]fs.FileInfo {
	return s.fileInfos
}

// Lstat implements System.Lstat.
func (s *ArchiveReaderSystem) Lstat(filename AbsPath) (fs.FileInfo, error) {
	fileInfo, ok := s.fileInfos[filename]
	if !ok {

View on GitHub (pinned to f901167e46)

Solutions

1. Rebuild the archive excluding special files (exclude /dev, sockets, fifos).
2. Convert special entries to regular files before archiving.
3. Use a mainstream archiver and standard formats (tar/pax) so modes are sane.

Example fix

# before
tar -cf dump.tar /var/run/mypipe /dev/sda
# after
tar --exclude='/dev/*' --exclude='*.sock' --exclude='*.pipe' -cf dump.tar myfiles/

// Skip entries with unsupported mode types before processing
if m := fi.Mode() & fs.ModeType; m != 0 && m != fs.ModeDir && m != fs.ModeSymlink {
    return fmt.Errorf("skipping special entry %s mode %o", name, m)
}

When it happens

Trigger: WalkFile over an archive containing entries with mode types like named pipes, devices, or sockets.

Common situations: Archives built from /dev or containing fifos/sockets; archives produced by tools that preserve special file types; corruption flipping mode bits.

Related errors

• %s: unsupported typeflag '%c'
• %s: unsupported file mode %o
• %s: unknown archive format
• %s: %w
• %s: unsupported mode %o

AI-assisted analysis of twpayne/chezmoi@f901167e46 (2026-09-01). Data as JSON: /api/errors/8fbcaf1b69be9027. Report an issue: GitHub.