Symptoms
When you try to upgrade from Windows Vista to Windows 7, from Windows Server 2008 to Windows Server 2008 R2, from Windows Server 2003 to Windows Server 2008 R2, or from Windows Server 2008 R2 to Windows Server 2012, the upgrade fails.In this situation, you receive the following error message:
The following issues are preventing Windows from upgrading. Cancel the upgrade, complete each task, and then restart the upgrade to continue.There is not enough free space on partition (drive:). A total of space_size megabytes (MB) of free disk space is required. Try Disk Cleanup, or moving files to an external location such as a CD, DVD, or external hard drive, and then restart the installation.
This problem does not occur during the new client setup experience for Windows 8.
Cause
This problem occurs when the size of the virtual memory paging file falls below the recommended limit. Windows upgrade requires that the page file be the recommended size and that sufficient space be available on the drive to accommodate a default sized page file. By default, Windows stores the paging file on the system volume. Therefore, there is insufficient free space on the system volume when you try to upgrade to Windows 7, Windows Server 2008 R2, or Windows 2012.
Resolution
To resolve this problem, use one of the following options.
Option 1: Free up space on the system volume
Use Disk Cleanup, or try to move files to an external location such as a CD, DVD, or external hard disk drive. Then, restart the installation. Make sure that required free space is available on the system drive. To free up space on your hard disk, Disk Cleanup finds and then removes temporary files on your computer that you decide you no longer need. If you have more than one drive or partition on your computer, you are prompted to select the drive that you want Disk Cleanup to clean.To start Disk Cleanup, click Start 
Option 2: Move the paging file to another volume
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Log on to the computer as Administrator.
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Click Start, right-click Computer, and then click Advanced system settings.
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In the System Properties dialog box, click the Advanced tab, and then click Settings under Performance.
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In the Performance Options dialog box, click the Advanced tab, and then click Change.
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Click to clear the Automatically manage paging file size for all drives check box.
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In the Drive [Volume Label] list, click a drive other than the one on which Windows is installed (typically, this is drive C). Under Total paging file size for all drives, note the value that is displayed next to Recommended.
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Check the Custom size box, and then type the recommended value in the Initial size (MB) box.
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Type the maximum size that you want to allow for paging in the Maximum size (MB) box, and then click Set.
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In the Drive [Volume Label] list, click the drive on which Windows is installed, click to select the No paging file check box, and then click Set.
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Click Yes when you are prompted.
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Click OK three times, and then restart the computer.
