Knowledge Base

You cannot select the Upgrade option when you try to install Windows Vista, and you receive a "Windows cannot determine if another operating system exists on your computer” error message

Article ID: 933166

Article Last Modified on 4/16/2007

APPLIES TO

Windows Vista Enterprise
Windows Vista Enterprise 64-bit Edition
Windows Vista Ultimate
Windows Vista Ultimate 64-bit Edition
Windows Vista Business
Windows Vista Business 64-bit EN
Windows Vista Home Premium
Windows Vista Home Premium 64-bit Edition
Windows Vista Home Basic
Windows Vista Home Basic 64-bit Edition

Symptoms of the problem

When you try to install Windows Vista, you cannot select the Upgrade option. Additionally, you receive the following error message in the Install Windows dialog box:

Upgrade has been disabled

- Windows cannot determine if another operating system exists on your computer. Try repairing the boot configuration, and then begin the installation again.

CAUSE

The location that is specified for the Windows directory is incorrect.

Steps to resolve the problem

To resolve this problem, start your previous operating system, and then edit the Boot.ini file to specify the correct location for the Windows directory. To do this, follow these steps.

Step 1: Save a backup copy of the Boot.ini file

Click Start, click Run, type sysdm.cpl, and then click OK.
In the System Properties dialog box, click the Settings button on the Advanced tab of the Startup and Recovery area.
In the System Startup area, click Edit. This step opens the file in Notepad for editing.
In Notepad, click File on the Menu bar, and then click Save As.
Right-click in an empty area of the Save As dialog box, point to New in the shortcut menu, and then click Folder.
Type a name for the new folder, and then press ENTER. For example, type temp, and then press ENTER to create a folder named temp.
Double-click the new folder named temp, and then click Save to save a backup copy of the Boot.ini file.

Step 2: Edit the Boot.ini file

Click Start, click Run, type sysdm.cpl, and then click OK.
On the Advanced tab, click Settings in the Startup and Recovery area.
In the System Startup area, click Edit.
Find the line in the Boot.ini file that contains the name of the previous operating system. For example, you may find a line that resembles the following.
```
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
```
If the Windows Vista Setup program created a partition in the unallocated disk space in front of the partition where a previous operating system is installed, the previous operating system partition must be marked as partition 2. In this scenario, you must increment the partition value by one. For example, if the Boot.ini file contains "partition(1)" for Windows XP, modify this text to "partition(2)." The modified line resembles the following.
```
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
```
After you make the correction, click Save on the File menu to save the new version of the Boot.ini file, and then exit Notepad.

Advanced troubleshooting

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

927295 You cannot select the Upgrade option when you try to install Windows Vista, and you receive the following message: “Windows cannot determine if another operating system exists on your computer”

Additional query words: Boot.ini Upgrade Vista has been disabled

Keywords: kbexpertiseinter kbceip kbcode kbprb kbtshoot kbsetup KB933166

Microsoft KB Archive/933166

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