# OST files are not included in backup

## Issue

> OST files are excluded from backup.

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## Cause

{% hint style="warning" %}
The exclusion of **OST** files is not accidental—learn more on the [**Microsoft Tech Community** website](https://techcommunity.microsoft.com/t5/storage-at-microsoft/why-completepc-backup-does-not-include-ost-files-in-the-backup/ba-p/423354).
{% endhint %}

**Xopero ONE** uses the **Microsoft Volume Shadow Copy Service** (**VSS**) for backup tasks. Certain files, such as deleted, temporary, paging, and **OST** files, are excluded from snapshots. This exclusion is managed by the `FilesNotToSnapshot` registry key in **Windows** registry. Consequently, these files are bypassed during the snapshot process and **are not included in the backup**.

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## Resolution

The excluded **OST** files can be found under `FilesNotToSnapshot` in **Registry Editor** (**regedit**)—you can include these files in **VSS** by removing specific values from the registry key:

1. Open **Registry Editor** (search box on the **Windows** taskbar > type **regedit** > select **Registry Editor**).
2. Navigate to `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot`.
3. Remove `OutlookOST` value.

<figure><img src="https://content.gitbook.com/content/0CBTl43C3OO6ySL1DJ6k/blobs/ayisSNZKdMsPHfX7kvXq/FilesNotToSnapshot%20registy%20key%20in%20the%20regedit.png" alt="FilesNotToSnapshot registy key in the regedit"><figcaption></figcaption></figure>