Run out of Space

Question

Why do I keep getting a notification that my back-ups could not be completed due to insufficient space when I have not used any cloud space as yet

Answer 1

Hello,

First, suspect that this email may not be a genuine Microsoft email. Do not click any links or enter your password. Genuine Microsoft emails usually use a legitimate domain like @microsoft.com.

Go to your Microsoft account's storage page and check:

OneDrive used space

Is your Outlook/Microsoft email account using up space?

Are there any files in the Recycle Bin?

https://account.microsoft.com/?refd=account.microsoft.com

Answer 2

The notification usually appears because the backup target or related storage is actually low on free space, even if cloud storage (like OneDrive) itself looks mostly unused.

On Windows and Microsoft 365 services there are a few common patterns:

1. Local disk or backup volume is low, not the cloud
   • Windows backup and similar tools check the free space on the local drive or target volume where the backup or shadow copies are created.
   • If that volume doesn’t meet the minimum free-space requirements, backups fail with “not enough space” even if OneDrive or other cloud storage is empty.
   • For example, Windows backup can fail with errors about insufficient space for volume shadow copies even when the disk appears to have space available.
2. Miscalculation or bug in space estimation
   • Some Windows backup components can incorrectly estimate required space and report “no sufficient free space on target volume” even when there is enough free space. This is due to how excluded data is counted during the backup space calculation.
3. Cloud vs. mailbox vs. device storage confusion
   • Microsoft accounts have separate quotas for:
     • OneDrive/cloud storage
     • Outlook.com mailbox storage
     • Local device disk space
   • A backup or sync process may be failing because local disk or mailbox space is low, while OneDrive still shows plenty of free space.

To move forward, check:

• Free space on the local drive/partition where backups are stored.
• Any error details in the backup tool (Windows Backup, OneDrive backup, etc.) to see which volume is reported as full.
• Storage settings in Windows (Settings → System → Storage) to confirm the device is not in a low-disk-space state.

If the local drive is low, free up space or change the backup target to a drive with more capacity, then rerun the backup.

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References:

• Windows backup fails with no sufficient free space on target volume in Windows Server 2012
• "The last backup did not complete successfully" error message when you back up a Windows 8 system
• Manage drive space with Storage Sense
• Why did I get a 'ran out of storage space' message in Microsoft To Do?