wagoodman/dive · error

cannot write to export file: %w

Error message

cannot write to export file: %w

What it means

Returned when writing the already-marshalled JSON bytes to the opened export file fails. The file was successfully created, but the actual Write call errored — typically disk full (ENOSPC), quota exceeded, or the file descriptor invalidated by an external actor. Note the file is opened without O_TRUNC, so pre-existing longer content can also leave stale trailing bytes on success.

Source

Thrown at cmd/dive/cli/internal/command/adapter/exporter.go:60

	})

	bytes, err := export.NewExport(analysis).Marshal()
	if err != nil {
		mon.SetError(err)
		return fmt.Errorf("cannot marshal export payload: %w", err)
	} else {
		mon.SetCompleted()
	}

	file, err := e.filesystem.OpenFile(path, os.O_RDWR|os.O_CREATE, 0644)
	if err != nil {
		return fmt.Errorf("cannot open export file: %w", err)
	}
	defer file.Close()

	_, err = file.Write(bytes)
	if err != nil {
		return fmt.Errorf("cannot write to export file: %w", err)
	}
	return nil
}

View on GitHub (pinned to d6c691947f)

Solutions

1. Check the wrapped error — 'no space left on device' means freeing disk or pointing --json elsewhere
2. Verify the target filesystem is writable and not quota-capped (df -h <dir>)
3. Re-run the export once space is freed; the payload is rebuilt from the in-memory analysis so a retry is safe
4. Operators of the exporter can add O_TRUNC to the OpenFile flags to avoid stale trailing bytes from previous longer files

Example fix

// before
file, err := e.filesystem.OpenFile(path, os.O_RDWR|os.O_CREATE, 0644)

// after (also truncate stale content)
file, err := e.filesystem.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)

// check free space before writing large exports
var stat syscall.Statfs_t
if err := syscall.Statfs(filepath.Dir(path), &stat); err == nil {
    free := stat.Bavail * uint64(stat.Bsize)
    if free < uint64(len(payloadEstimate)) { return fmt.Errorf("insufficient space for export") }
}

err := exporter.ExportTo(ctx, analysis, path)
if err != nil && strings.Contains(err.Error(), "cannot write to export file") {
    // transient ENOSPC/EIO: free space or change path, then retry once
    err = exporter.ExportTo(ctx, analysis, altPath)
}
if err != nil { return err }

When it happens

Trigger: dive --json <path> where the disk fills during the write, a filesystem quota is hit, the filesystem is read-only remounted between open and write, or an antivirus/container runtime holds/invalidates the fd.

Common situations: CI runners with small ephemeral disks writing large image exports; exporting into a full volume mount; overlay filesystems in containers hitting disk pressure.

Related errors

• cannot open export file: %w
• cannot export analysis: %w
• directory for JSON export does not exist: %s
• cannot marshal export payload: %w
• unable to read file: %w

AI-assisted analysis of wagoodman/dive@d6c691947f (2026-08-15). Data as JSON: /api/errors/619cae32fe35ced5. Report an issue: GitHub.