Similar to the NTLDR for Windows XP and earlier versions, BOOTMGR the abbreviation for Boot Manager helps operate the system menu to manage unique systems.
The "BOOTMGR is compressed" error is very common, because of which you might not be able to enter the desktops of any of the operating systems. The error may be as follows:
BOOTMGR is missing. Press Ctrl+Alt+Del to restart
Your windows installation disc provides an option to fix this error. All you have to do is install the DVD, and select "Repair my Computer". Upon this, you will have OS installation, and after browsing into "Load Drivers" all you have to do is deselect the "Compress my Computer" option! Apply the changed settings onto your files and subfiles, and then reboot your system, the error will hopefully be gone now.
Your Windows Installation Disc or bootable media provides system recovery options to fix a "BOOTMGR is Compressed" error.
1. Boot from the Windows Installation DVD or bootable media. Set CD/DVD-ROM/USB bootable media as the first boot device if not set already.
2. Select "Repair My Computer"
3. Select the OS installation; click the "Load Drivers" button to bring up a drive browser.
4. Right-click on the system drive, and deselect "Compress This Drive", which should still be selected (That's why the "BOOTMGR is Compressed" error has occurred).
5. Click "Apply", in the pop-up dialog box, choose "Apply to Subfolders/files".
6. Reboot your computer and the "BOOTMGR is Compressed" error should be repaired.
By the way, ntldr compressed error also occurs sometimes.
As do other errors in our computers, this error is often seen as well. It is highly likely that when this error is developed into your computer, the system fails to boot up. Even at times when you're trying to fix the issue with the above solutions, you can't make it out.
If you do encounter a failure of booting the computer after you've fixed the "BOOTMGR is compressed" error, Recoverit Data Recovery can help you out. It helps you to create a bootable media and recover data on the unbootable computer. You can follow the below steps to go on: