How To Fix BOOTMGR Is Compressed Error Message

The following error message may appear at startup:

BOOTMGR is compressed

Press Ctrl+Alt+Del to restart

There is no way to boot (start up) to Windows – pressing Ctrl+Alt+Del just restarts the computer and redisplays the same message.

I saw this error recently on a customer’s computer and though I’d share how to fix it – it can affect XP, Vista or Windows 7 computers.

Cause
BOOTMGR refers to the Boot Manager – an important Windows system file. If it is compressed, it can’t be used.
The file must therefore be uncompressed for Windows to be able to boot up.
Note: file compression used to be a good way to save hard drive space – back in the days when hard drives were only 1 or 2 GBs in size… However, modern drives offer hundreds or thousands of GBs storage so there should be no need to compress files.

Bootmgr is Compressed error

How Did It Get Compressed?
There are two likely reasons:
1. The user installed a ‘Speed Booster’ or ‘System Optimizer’ type of program – perhaps one with grand claims of boosting performance and with a super duper registry cleaner thrown in… See ‘do I need a registry cleaner’ – the short answer is No.
Such a program may have caused the problem by compressing the whole of the system partition (usually the C: drive) to save space – including the crucial BOOTMGR file. This is what happened in my customer’s case.
Note: file compression (even when done properly) slows down system performance anyway so it is a lousy thing for a ‘speed booster’ utility to do…
2. The user manually compressed the whole of the system partition (via the drive’s Properties window).
How To Fix It?
There are similar fixes for XP and Vista/7 – both require you to recreate the boot record:
XP
You will need to have a bootable XP installation CD available.
Log into the Recovery Console command prompt by following steps A to F in my article on fixing ntldr.
You should now be in the C:\Windows directory.

• Type fixmbr and press Enter. Press Y to proceed

• Type fixboot and press Enter. Press Y to proceed

• Type Exit and press Enter to restart the computer

The BOOTMGR is compressed error message should not appear and Windows should boot normally.
Vista/7

Boot into the System Recovery Options using the preinstalled Advanced Boot Options or a Vista/7 installation/recovery DVD – see the illustrated tutorial at Sevenforums for instructions if required.

• Select ‘Startup Repair’ and wait until the repair attempt completes. If successful you can then restart the computer and Windows may boot up normally.

If the repairs fail and/or the computer does not restart into Windows normally, proceed as follows.

• Boot into the System Recovery Options again but this time select ‘Command Prompt’ instead of startup repair – this will take you to a windows command prompt.

• Type bootrec /fixmbr and press Enter. Press Y to proceed

• Type bootrec /fixboot and press Enter. Press Y to proceed

• Type bootrec /rebuildbcd and press Enter. Press Y to proceed

• Type Exit and press Enter to restart the computer.

The BOOTMGR is compressed error message should not appear and Windows should boot normally.

If Previous Fixes Fail
This step should not be required but, if the previous fixes failed to resolve the problem, you may need to uncompress all files on the system partition manually.

• Log into the Recovery Console command prompt (XP) or the System Recovery Options \ Command Prompt (Vista/7)

• Type  compact /u /a c:\*.*  and press Enter. The command may take a long time (hours) to complete on a very large drive – leave until finished

The command uncompresses (/u) all files (*.*) on the c:\ drive including hidden and system files (/a).
Note: if your system drive is not c: then change the c in the command to your drive letter

• Once the command finishes uncompressing all files, type Exit and press Enter to restart the computer.

The BOOTMGR is compressed error message should not appear and Windows should boot normally.

Conclusion
Unfortunately Windows does nothing to prevent an ‘optimizing’ program or a user from compressing the boot manager – even though Windows will not boot if Bootmgr is compressed…
However, this problem is relatively straightforward to fix and easy to avoid in future – don’t use system optimizing utilities that may compress the system partition and don’t try to compress it manually.