Over one million Mac users rushed on the first day to download and install the new OS X Lion. Lots of them didn’t even have a Time Machine backup.

Now problems are surfacing: the Apple Support Community is bombarded with messages from people having issues during the upgrade.

Some are stuck with no OS working, some with multiple partitions on their HD are unable to install, some can’t seem find their HD!

The most common error messages users are getting are “This disk cannot be used to start up your computer.” or “Lion cannot be installed on this drive.”

This will happen even if you run the Drive-Verification and Repair Disk permission in Disk Utility.

It appears that users with an HD that has been previously restored from a Time Machine backup are experiencing this issue. The HD will have a folder called “Backups.backupdb” on it, and for some reasons Lion seems to recognize the drive as a backup drive. That’s why that error message.

Users with multiple partitions using bootcamp are also experiencing problems.

This workaround should fix both these cases:

1. Restart your Mac and open Disk Utility (Applications > Utilities)

2. Select your disk from the left-hand side column and select the Partition tab.

3. In the Partition Layout, click and drag and resize your intended install partition to a slightly smaller size (150 MB is enough)

BEFORE                                                         AFTER

 

4. Click Apply

5. Quit Disk Utility and install OS X Lion