Mac Error Code -56 — No Such Driver (nsDrvErr)

Mac error code -56 indicates a missing or incompatible driver, commonly seen when connecting external devices or storage media. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Error -56 (nsDrvErr) is a classic Mac OS driver error code. Indicates the system cannot find a driver for the requested device. Common with external drives formatted for other operating systems. Can appear when mounting USB drives or network volumes. Legacy error code still surfaced in some modern macOS operations. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: External drive formatted with an unsupported filesystem (ext4, NTFS write). Missing driver for specialized USB or Thunderbolt device. Corrupted disk driver partition on external drive. USB hub or adapter incompatibility. Third-party filesystem driver not loaded or corrupted. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Check the drive format in Disk Utility — APFS, HFS+, and exFAT are natively supported. For NTFS write access, install a third-party driver like Paragon NTFS or Mounty. Try connecting the device directly without a USB hub. Try a different cable and port — USB-C ports are preferred on modern Macs. If the drive was used on Windows, safely eject it there before connecting to Mac. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Mac Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.