Error 0x80070070 means Windows ran out of disk space while trying to complete an operation.
Microsoft identifies the underlying Windows error as ERROR_DISK_FULL. In the Windows Update context, Microsoft states that the error occurs when there is not enough space to store the update files needed for installation. [R1] [R2]
This is therefore one of the Windows Update errors with a relatively clear meaning:
Freeing enough space should come before repairing Windows Update itself.
Which drive needs space?
Usually, the important drive is the Windows system drive, normally C:.
An update may need space to download files, unpack them, prepare installation data, and retain information Windows needs while the update is being applied.
Having plenty of free space on another drive does not necessarily solve the problem if the Windows system drive is full.
Microsoft currently recommends having at least 20 GB available on the operating-system disk for best results when resolving this error. [R1]
Treat that as troubleshooting guidance rather than a guarantee that every individual update consumes 20 GB.
What should I remove?
Start with Windows' own storage-management tools rather than manually deleting files from Windows folders.
In Windows 11, open:
Settings → System → Storage → Cleanup recommendations
Windows can identify categories such as temporary files, unused applications, large files, and other content that may be removable. [R3]
Storage Sense can also remove unnecessary temporary files and manage Recycle Bin contents according to its settings. [R3]
You can additionally:
- Remove applications you no longer use.
- Move large personal files such as videos or archives to another drive.
- Empty the Recycle Bin after checking its contents.
- Make suitable OneDrive files online-only instead of keeping local copies.
Review what Windows proposes before deleting it.
Do not delete Windows system files manually
A large file or folder is not necessarily safe to remove.
Do not manually delete unfamiliar files from locations such as the Windows directory merely because they consume substantial space. Use Windows' supported cleanup tools instead.
Be particularly careful with Previous Windows Installation / Windows.old. Windows may offer it as cleanup content, but Microsoft warns that removing it also removes the ability to return to the previous Windows version. [R3]
That cleanup therefore has a real cost.
Can an external drive help?
For some Windows updates, Windows can use an external storage device to provide additional temporary space. [R3]
This can be useful on PCs with small internal drives.
However, external storage does not eliminate every internal-space requirement. Windows may still ask you to free some space on the system drive before installation can continue.
What if C: does not look full?
Confirm how much space is actually available on the Windows drive.
Open File Explorer → This PC and check the free-space value shown for the system drive.
If substantial free space is available but Windows Update repeatedly reports 0x80070070, the finding needs further investigation rather than repeated cleanup. The error identifies a failure to obtain enough disk space for the operation, but the surrounding Windows Update evidence should be checked to determine where that space was required. [R1]
Do not automatically reset Windows Update components, run DISM, or reinstall drivers merely because this code appeared. Those actions address different problems and do not create the missing storage capacity.
What should I do now?
- Check the free space on the Windows system drive.
- Open Settings → System → Storage.
- Review Cleanup recommendations.
- Remove temporary or genuinely unwanted files and unused applications.
- Move large personal files elsewhere if necessary.
- Aim for substantial free space; Microsoft recommends at least 20 GB on the operating-system disk when troubleshooting this error. [R1]
- Retry Windows Update.
- Confirm that the original update now downloads and installs successfully.
See also: disk-nearly-full
A successful repair means the original Windows update installs without error 0x80070070. Freeing several gigabytes without successfully completing the update is not, by itself, proof that the incident is resolved.