benbjohnson/litestream · error

acquire exclusive lock: %w

Error message

acquire exclusive lock: %w

What it means

applyLTXFile could not acquire the exclusive file lock on the followed database before writing pages. Another process (a SQLite reader/writer or second litestream) holds the file, so the apply is aborted to avoid partial updates.

Source

Thrown at replica.go:961

// (bytes 18-19) to indicate DELETE journal mode instead of WAL mode, and
// randomize the schema change counter (bytes 24-27) to invalidate cached
// schemas in other connections.
func (r *Replica) applyLTXFile(ctx context.Context, f *os.File, info *ltx.FileInfo, pageSize uint32) error {
	rc, err := r.Client.OpenLTXFile(ctx, info.Level, info.MinTXID, info.MaxTXID, 0, 0)
	if err != nil {
		return fmt.Errorf("open ltx file: %w", err)
	}
	defer rc.Close()

	dec := ltx.NewDecoder(rc)
	if err := dec.DecodeHeader(); err != nil {
		return fmt.Errorf("decode header: %w", err)
	}

	hdr := dec.Header()

	if err := internal.LockFileExclusive(f); err != nil {
		return fmt.Errorf("acquire exclusive lock: %w", err)
	}
	defer internal.UnlockFile(f)

	for {
		var phdr ltx.PageHeader
		data := make([]byte, pageSize)
		if err := dec.DecodePage(&phdr, data); err == io.EOF {
			break
		} else if err != nil {
			return fmt.Errorf("decode page: %w", err)
		}

		if phdr.Pgno == 1 && len(data) >= 28 {
			data[18], data[19] = 0x01, 0x01
			_, _ = rand.Read(data[24:28])
		}

		off := int64(phdr.Pgno-1) * int64(pageSize)

View on GitHub (pinned to 4ed7a308f6)

Solutions

1. Stop concurrent accessors of the followed database file
2. Ensure only one litestream follow process runs per database

When it happens

Trigger: Thrown at replica.go:961 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of benbjohnson/litestream@4ed7a308f6 (2026-09-06). Data as JSON: /api/errors/3618f4dd70ae0d65. Report an issue: GitHub.