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. 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.

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.

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 is no need to compress files. There are two likely reasons that it got compressed:

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) may slow 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).

bootmgr is compressed

Bootmgr is Compressed error

How To Fix It? There are similar fixes for XP and Vista/Windows 7 – both require you to recreate the boot record:

XP – You will need to have a bootable XP installation CD available.

1. 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.
2. Type fixmbr and press Enter. Press y to accept the warning and proceed:



3. Type fixboot and press Enter. Press y to to confirm and proceed:



4. Type Exit and press Enter to restart the computer. The error message should not appear and Windows should start up normally.

Vista/Windows 7 – Boot into the System Recovery Options using the preinstalled Advanced Boot Options or a Vista/Windows 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:

1. 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.

[Note: if using RAID for multiple hard drives you may not see your version of Windows listed in System Recovery Options, during the loading of the recovery process. In this case you would need to press ‘Load Drivers’ and browse to your RAID drivers so that your version of Windows can be listed]

2. Type bootrec /fixmbr and press Enter.
3. Type bootrec /fixboot and press Enter.
4. Type bootrec /rebuildbcd and press Enter. Type Y and press Enter if asked to add the installation to the boot list:


Bootrec commands

5. Type Exit and press Enter to restart the computer. The error message should not appear and Windows should start up 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/Windows 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

Note: if your system drive is not c: then change the c in the command to your drive letter.

The command uncompresses (/u) all files (*.*) on the c:\ drive including hidden and system files (/a). Once the command finishes uncompressing all files, type Exit and press Enter to restart the computer. The error message should not appear and Windows should start up normally.


Unfortunately Windows does nothing to prevent an ‘optimizing’ program (or a user) from compressing the boot manager – even though it means that Windows will not boot. 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.

171 Responses to: "How To Fix BOOTMGR Is Compressed Error Message"

  1. guovay says:

    can u use the windows vista installation disk to fix that problem in windows7

  2. tsaker daniel says:

    i used the bootmgr compressed instructn and it worked for me. So i want to say thank u very much. U r a blesin to me

  3. kimberlie says:

    I love you !
    I got my win xp pro netbook back. After i did something stupid – yeah i compressed the drive.
    I Love you and will bake for you in gratitude becuase I just cld not with one more problem today.

  4. thida says:

    i am very thank u that can help solve the problem to fix the bootmg compressed computer, cause i have did something stupid on it

  5. Anish says:

    Thanks a lot…this site really provided the correct option….

  6. Benie says:

    Wow wow wow….I just wanna say thank you thank you soooo much….u just saved a Business…
    God Bless you..

  7. Zain says:

    This really worked for me… Thanks a lot.

  8. Phil says:

    Do you need a burner to create a w7 recovery disk?

    • Roy says:

      Yes, you need a CD or DVD (re)writer to burn a disc – W7 laptops/PCs should have one, netbooks don’t (ask a friend) – or use a full W7 installation disc if you can borrow one

  9. Carl Freeman says:

    I love you too! Having tried to help my sister-in-law with a slow laptop, with a full to bursting C drive but empty D drive partition, we went for the compress this drive option. It said it was going to take something like 47154 days and 16 hours so after a few mins, we cancelled it. Then we found we could not boot. I tried several possible solutions found on line, but yours is the only one that worked. I am so happy I could almost cry. Thank you so so much. You are a super hero. The next thing I will do is set up system restore points on her lap top. Thanks again. Seriously, thank you so much!!!!

    • Roy says:

      Thanks Carl. If D partition is empty you should be able to move the user docs/music/pictures folders there which may save a lot of space on C partition

      [Ideally if D is empty you would delete the partition and expand C to fill all the available hard drive space but that is a more advanced job – don’t mess with repartitioning unless you really know what you’re doing – and have a full backup if it goes pear shaped]

      • Carl Freeman says:

        I have started copying data files over to the D partitition, Roy. I cannot however create a restore point as rstrui.exe is missing! My sister-in-law’s ex downloaded somestuff a while back and a nasty virus caused all sorts of issues. I am guessing this was one of a number of key files. There is no backup and no system disk. One for another day I think!

        Best wishes,


  10. fredrik says:

    Thank you so much! :D

  11. Yan S says:

    Worked like a charm with the command prompt, thanks.

  12. Bessaca says:

    Man I used your advice and it worked…u are a blessing to me (bootmgr compressed) problem.

  13. Vaf23 says:

    I have an advent netbook with same problem but no disk drive and no windows recovery cd. What can I do?
    Thank you.

    • Roy says:

      Do you not get any system recovery options (vista/7) when you press F8 at startup as described?

      If not, or you have XP and no Recovery Console, you may need to take hard drive out and uncompress it from another computer or else boot up from an external USB DVD drive (if you can borrow an installation DVD or recovery CD to use in it)

      • Vaf23 says:

        Hi. Thanks for reply
        I can get into boot screen but no recovery console. I did take had out and put into an enclosure to save all my files. I did uncompress it, or so I thought, but when put back into netbook I still got same bootmgr compressed message! I’m kind of new to computer DIY so must be doing something wrong. Any help you can give would be great. Thanks again.

      • Roy says:

        Ok, pop hard drive back into USB enclosure and plug into the other computer then right click the enclosure drive letter (in Computer/Explorer) and choose ‘Properties’ then UN-TICK ‘Compress drive to save disk space’ to uncompress the drive – may take a long time as USB is slow

        If it was NOT ticked – open a command prompt and type compact /u /a c:\*.* (but replace c with the drive letter of your USB enclosure/drive!) and press Enter – leave until finished. Should uncompress everything

  14. Ananthi says:

    Thank you so much.. Let you be blessed with lot of technical stuff..

  15. Kola says:

    Tnx, u are really a life saver, it works 4 me