"You must enable rollback to continue with setup" error message appears when you install or remove .NET Framework (312499)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you install or remove the .NET Framework, you may receive the following error message:

You must enable rollback to continue with setup. For more information, please visit http://support.microsoft.com/support/kb/articles/q312/4/99.asp

CAUSE

This error occurs because the rollback feature of the Microsoft Windows Installer is disabled. The .NET Framework Setup program requires commit custom actions for proper installation. Rollback and commit custom actions do not run when rollback is disabled.

Rollback is disabled in the DisableRollback policy in the registry. The DisableRollback policy value may have been set by an administrator. Microsoft recommends that administrators do not disable rollback unless this is necessary.

RESOLUTION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

There are two places in the registry where the DisableRollback policy value can be set. To resolve this problem, you must find out where the DisableRollback policy was set and remove or disable the setting.

To find out whether this property exists in your registry, run C:\Regedit.exe and check the following locations:

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Installer\DisableRollback

HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Installer\DisableRollback

If the DisableRollback key exists and has a value of "1", delete the key or set the value of the key to "0". (You can also set DisableRollback through command-line instructions.) Microsoft recommends that administrators and developers not set this property if they use command line instructions to run Setup, or Setup will not work.

MORE INFORMATION

For more information about the DisableRollback policy value, visit the following Microsoft Developer Network (MSDN) Web site:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/msi/setup/machine_policies.asp