How to Fix BOOTMGR is Compressed in Windows 7

If the above method doesn’t work or you can’t boot into Safe Mode, you can try the following alternative solutions:

Use Startup Repair

Boot from the Windows 7 installation DVD or USB drive.
Click “Repair your computer” in the lower-left corner.
Select your Windows 7 installation and click “Next”.
In the System Recovery Options menu, select “Startup Repair”.
Follow the on-screen instructions to diagnose and fix startup issues.

Manually Update BOOTMGR

Boot from the Windows 7 installation DVD or USB drive.
Click “Repair your computer” in the lower-left corner.
Select your Windows 7 installation and click “Next”.
In the System Recovery Options menu, click “Command Prompt”.
Type the following command and press Enter:
bcdboot C:\Windows /s E:

Replace “C:\Windows” with the actual path to your Windows installation folder and “E:” with the drive letter of your active boot partition.
Restart your PC, and the “BOOTMGR is compressed” error should be resolved.
If none of the above methods work, it’s possible that your Windows 7 installation is corrupted or damaged. In such cases, you may need to perform a clean reinstallation of Windows 7 to resolve the issue.
Remember to always have a backup of your important data before attempting any major system repairs or reinstallations.