How to Save System Files During Setup (305087)

MORE INFORMATION

When you upgrade your Windows operating system, you are normally offered the option to save your current system files. This information is used to uninstall the new operating system and return it to the earlier configuration. This can be essential for recovering your system if an error occurs during the setup process.

NOTE: Failure to save this information prevents you from reverting the system to the earlier operating system.

This process is not the same as performing a system backup. Microsoft recommends that you back up your files completely before you upgrade your operating system. The Save System Files option is designed only to restore the operating system to an earlier installation. It does not save any other data on your system.

This option may also be available during a reinstallation of the operating system.

Save System Files Option Is Not Available During Setup

If the Save System Files option is not available during the setup process, please click the article number below to view the article in the Microsoft Knowledge Base:

232614 The "Save System Files" Dialog Box May Not Be Displayed

File Names and Location

The uninstall information is normally stored in the root directory of the drive on which you are installing Windows.

The following system files are used by the given operating systems:

Windows 98:

Winundo.dat
Winundo.ini
Winlfn.ini

Windows 98 SE:

W98undo.dat
W98undo.ini
Winlfn.ini

Windows Me:

W9xundo.dat
W9xundo.ini
Winlfn.ini

How to Remove Uninstall Information from Your System

The files used to store your uninstall information can typically be several hundred megabytes in size. This can be a significant amount of hard-disk space on some computer systems. Therefore, you have the option to remove this information from your system.

WARNING: By removing this information, you will no longer be able to uninstall the operating system and revert to the earlier installation. It is not recommended that you remove these files unless you are certain that you will not need to revert to the earlier installation of your operating system.

To remove these files, follow these steps:

Click Start, point to Settings, and then click Control Panel.
Double-click Add/Remove Programs.
Select the Delete Windows Millennium uninstall information option.
Click the Add/Remove button.

How to Reinstall the Same Operating System

When you reinstall the same operating system, the previously saved uninstall information files can be overwritten. To prevent this behavior from occurring, you should back the files up to another location.

For additional information about backing up your uninstall information, click the article number below to view the article in the Microsoft Knowledge Base:

195384 How to Save the Uninstall Files Before the Reinstallation of Windows