File History Drive Disconnected — Backup Drive Not Found or Unavailable

Fix Windows File History error when the backup drive is disconnected, not recognized, or becomes unavailable for automatic file backups. 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: File History continuously backs up personal files to an external drive or network location. When the backup drive is disconnected, File History queues changes and syncs when reconnected. Prolonged disconnection means many file versions are lost and not backed up. File History supports USB external drives, network shares (SMB), and NAS devices. The backup drive must remain connected or regularly reconnected for File History to work. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: USB external drive physically disconnected or USB port not providing power. Network share or NAS is offline, moved, or has changed authentication credentials. Drive letter changed after reconnecting the USB drive to a different port. Backup drive is full and File History cannot write new versions. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Reconnect the backup drive and check if File History resumes: Settings > Update & Security > Backup. For network drives: verify the share is accessible by typing \\server\share in File Explorer. If drive letter changed: remove the old drive in File History settings and re-add with the new letter. Free space on the backup drive or switch to a larger drive in File History settings. Run File History manually to catch up: winfh -backupnow from an admin Command Prompt. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

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