Back up the AppData folder in Windows

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By default, the CrashPlan app backs up your User folder, which contains the AppData folder for your Windows computer. Files in this folder update frequently. Consequently, your backup may not be reaching 100% if this folder is kept in your backup set. This article explains what the AppData folder is so that you can determine whether you want to keep it in your file selection.

What is the AppData folder?

AppData is a hidden folder located in C:\Users\<username>\AppData. The AppData folder contains custom settings and other information needed by applications. For example, you might find the following in your AppData folder:

  • Web browser bookmarks and cache
  • Application configuration files
  • Temporary files


In CrashPlan, many folders in the AppData folder are already excluded from backup by default. See What is not backing up? for more information.

The CrashPlan app and AppData

Certain files inside AppData can fail to back up with the CrashPlan app. When this happens, your email reports show less than 100% backed up, and CrashPlan's History log displays the message Unable to backup n files. This happens because the files in this folder:

  • are open and locked by the application that created them.
  • were not created with the correct permissions for the CrashPlan app to back them up.
Should I be worried?
This is rarely a cause for concern. Files that fail to back up from the AppData folder are typically temp files that do not need to be restored. CrashPlan is designed to protect your user files (Desktop, Documents, and Pictures), not your entire operating system and applications.

Examples of AppData files that commonly fail to back up

C:\Users\<username>\AppData\Local\Microsoft\Internet Explorer\Recovery\High\Active*.dat
C:\Users\<username>\AppData\Local\Google\Chrome\User Data\Default\Current Session
C:\Users\<username>\AppData\Local\Google\Chrome\User Data\Default\Current Tabs
C:\Users\<username>\AppData\Local\Google\Chrome\User Data\lockfile

Should I just remove the AppData folder from my backup?

Because most applications only store their configuration settings in this folder, and not the files you create, it's often not necessary to back it up. However, there may be exceptions such as older versions of Outlook.

Review the files in your AppData folder to determine whether or not you want to back it up before removing it from your backup.

Remove AppData

If you have permission, you can change the file selection in the CrashPlan app. If you decide to change your file selection to remove the AppData folder:

  1. When changing your file selection, select Show hidden files to reveal the AppData folder.
  2. Expand the AppData folder and check for any subfolders you may want to continue backing up (such as your web browser's bookmarks or your Outlook PST files).
  3. If you're not sure what you need, leave AppData selected and troubleshoot the unable to backup n files issue if you see files within AppData failing to back up.

Administrators can change the file selection from the CrashPlan console:

Location of Outlook PSTs

Depending on what version of Outlook you are using, you may or may not want to back up your AppData folder. 

  • Versions of Outlook prior to Outlook 2010 store your PST files (Personal Folders, commonly used for archiving mail) in your AppData folder: C:\Users\<username>\AppData\Local\Microsoft\Outlook\. In this case, you may need to back up your AppData folder.
  • Later versions of Outlook don't store PST files in your AppData folder. Instead, they are stored in C:\Users\<username>\Documents\Outlook Files\, which the CrashPlan app backs up with the rest of your Documents folder. In this case, you may not need to back up your AppData folder.
  • Microsoft Exchange, Office 365, and email accounts are automatically backed up on the email server. In most cases, you won't have a PST file for these types of accounts.

If you're not sure where your Outlook PSTs are located, see this article from Microsoft: How to manage .pst files in Microsoft Outlook.

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