Partition Becomes Unallocated After Windows 10 Upgrade

Table of Contents

A Windows 10 upgrade can expose disk problems or fail while updating partition information. A former partition may then appear as unallocated.

Background and causes

Do not create a new volume immediately. New partition information can overwrite traces needed for recovery.

Confirm the exact disk, partition, drive letter, file system, and capacity before changing anything.
Recover or back up important files before formatting, deleting, converting, or recreating partitions.
For boot-related changes, check BIOS/UEFI mode and boot order before editing disk layout.

Open Disk Management, note disk number and capacity, check SMART health, and recover files before rebuilding the partition.

Qiling Disk Master

Recover files before formatting, deleting, or rebuilding the problem partition.

Step 1. Open Deep Data Recovery and choose Fast Scan.

Choose Fast Scan

Step 2. Select the lost, RAW, or unallocated location and start scanning.

Select scan location

Step 3. Preview files and recover them to another healthy disk.

Recover selected files

After files are recovered, create a new partition only on the correct unallocated space and restore data from the recovery destination.

How to Recover Data
Recover lost files before formatting, deleting, or rebuilding a partition.
Unallocated Partition Recovery
Recover data from a partition that becomes unallocated or invisible.