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File History Drive Disconnected — Backup Drive Not Found or Unavailable

Warningsystem

Overview

Fix Windows File History error when the backup drive is disconnected, not recognized, or becomes unavailable for automatic file backups.

Key Details

  • 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

Common Causes

  • 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

Steps

  1. 1Reconnect the backup drive and check if File History resumes: Settings > Update & Security > Backup
  2. 2For network drives: verify the share is accessible by typing \\server\share in File Explorer
  3. 3If drive letter changed: remove the old drive in File History settings and re-add with the new letter
  4. 4Free space on the backup drive or switch to a larger drive in File History settings
  5. 5Run File History manually to catch up: winfh -backupnow from an admin Command Prompt

Tags

file-historybackupdrivedisconnectedexternal-drive

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windows-backup-failed-error-0x81000019

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Frequently Asked Questions

File History tracks which files changed while the drive was disconnected. When the drive reconnects, it backs up the latest versions of changed files. However, intermediate versions (changes between disconnection and reconnection) are lost.