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My Windows 10 C: drive was almost completely full. Its capacity was only about 31.45 GB, while Disk Management showed another 18 GB of unallocated space on the same disk. Expanding C: looked straightforward, but a small recovery partition stood in the way. Then disabling Windows Recovery Environment failed because the drive was too full.

Why Windows could not extend C:

I opened Disk Management with Win+R and diskmgmt.msc. The partitions appeared in this order:

The recovery partition separated C: from the unallocated space. Windows’ built-in tools require adjacent unallocated space after the volume to extend it. Increasing a virtual disk in the hypervisor does not automatically extend its Windows partition.

Check which partition contains WinRE

The approach was to disable WinRE, remove the blocking recovery partition, and extend C:. Before changing partitions, take a backup or VM snapshot. The disk and partition numbers below apply to this particular machine; verify them on your own system.

From an administrator Command Prompt, I checked the recovery configuration:

reagentc /info

WinRE was enabled, and its location identified disk 0, partition 3:

\\?\GLOBALROOT\device\harddisk0\partition3\Recovery\WindowsRE

The unexpected error: REAGENTC failed with 70

I tried to disable WinRE:

reagentc /disable

The command failed with error 70. Running reagentc /info again still showed WinRE as enabled. To investigate, I searched the log:

findstr /i /c:"error" /c:"fail" /c:"70" C:\Windows\Logs\ReAgent\ReAgent.log

The relevant entries were:

winreCopyWIMBack failed to move WIM file from \\?\GLOBALROOT\device\harddisk0\partition3\Recovery\WindowsRE\ to C:\Windows\system32\Recovery\Winre.wim: 0x70
-----Exiting command line: reagentc /disable, Error: 112-----

Here, 0x70 is hexadecimal for decimal 112: ERROR_DISK_FULL. The operation was trying to copy Winre.wim back onto C:, where there was insufficient space. Unallocated disk space could not help until it became part of the volume.

Free enough space to disable WinRE

The immediate task was to free space on the existing C: volume. Disk Cleanup can be started with:

cleanmgr

Select C: and use Clean up system files, reviewing the categories before deleting anything. Aim for roughly 1–2 GB of free space; the actual requirement depends on the recovery image and other activity on the machine. Check the available space with:

fsutil volume diskfree C:

After freeing space, I retried:

reagentc /disable

This time the operation completed successfully. That resolved the blocker. The remaining steps below describe the extension procedure and its final checks.

Remove the blocking partition and extend C:

First confirm WinRE is disabled and the recovery image is present on C: before removing its old partition:

reagentc /info
dir /a C:\Windows\System32\Recovery\Winre.wim

Then inspect the partition in DiskPart:

diskpart
list disk
select disk 0
list partition
select partition 3
detail partition

Continue only if the selected partition is the verified 509 MB recovery partition. Do not delete C:, System Reserved, or an EFI System Partition. If the layout differs, do not copy these partition numbers.

Once verified, remove that recovery partition and extend C: into the contiguous free space:

delete partition override
select volume C
extend
exit

For this layout, using all the available space should bring C: to approximately 49.9 GB. Verify the result in Disk Management and with:

fsutil volume diskfree C:

Check the recovery environment afterwards

Re-enable WinRE and inspect its status:

reagentc /enable
reagentc /info

Check for Enabled and a valid recovery image location. Do not assume that enabling WinRE recreates the deleted recovery partition. A dedicated recovery partition may need to be created and configured separately, particularly with an encrypted OS volume. If enabling fails, inspect the ReAgent log and restore a suitable WinRE configuration.

The successful output captured during this troubleshooting session confirms that WinRE was disabled. The final disk size and WinRE re-enable result still require the checks above.

The main lesson from this exercise was that expanding a full Windows volume can first require freeing space on that same volume: disabling WinRE needed room to move its recovery image.

References

Microsoft: Windows system error codes; Microsoft: a recovery partition blocking volume extension; Microsoft: REAgentC command-line options.