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.

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

  1. drill says:

    It’s dope , I am alive again

  2. Kealeboga says:

    im using xp and i have lost my installation cd so what must i do?

  3. Hafthor says:

    Thanks Roy, It was a bit unclear to me too :) I was searching for this command you mentioned, that is bootrec and fixboot. I didn´t remember bootrec.
    Yes I have to use the W/ Startup repair disc to do this.

  4. Hafthor says:

    Hi, when i install Ubuntu next to Win 7 and then delete it my bootloader constantly want to boot up Ubuntu. So I have to fix that. I have used fixboot just as you mention but it doesn´t work till I use mbr but I have forgot the parameter.
    I had pdf file showing it but it´s corrupt and now I am bit lost.

    How can I fix this?


  5. Laura says:

    Working on computer….Bootmgr is compressed is on screen. I pressed alt ctrl and del and nothing happen. I have windows on my toshiba computer

  6. nandlal says:

    Thanks i have the problem and you have the solution :-D:-D;-);-)

  7. katy morris says:

    Mine booted correctly again after first instructions and there I was where my battery had died during compression. I pushed cancel and have since been working on uncompressing the one that had completed before my cord got unplugged. Oh, and a current backup. Although, when I was in restore mode it didn’t find any of my backups even tho I have them on my external 640gb HD. If I find the disk I bought a program about two years ago called spotmau. Heard of it? Think it’s worth the money to renew?

    • BillyB says:

      can’t say i’d ever heard of it and a quick search brings very mixed reviews – for image backup i’d suggest Acronis true image or Macrium reflect if you want a free one

      • katy morris says:

        Ya, this spotmau one is actually pretty good. Even gets ya in if you don’t remember your windows password. Haha. That’s how I ended up getting it. You can transfer files off a hard drive that won’t boot. Etc.

  8. Steve says:

    In the section “If Previous Fixes Fail” is there a reason not to uncompress bootmgr and/or boot files instead of all files (although hiberfil.sys and pagefile.sys that are also found in the root shouldn’t be compressed either)?

    The commands should be:

    compact /u /a c:\bootmgr
    compact /u /a /s c:\boot (I believe these too need to be uncompressed)

    I doubt the following are required, but if bootmgr in other locations also needed to be uncompressed, the following should do that:

    compact /u /a /s c:\windows\boot
    compact /u /a /s c:\windows\system32\reminst

    • Roy says:

      @Steve – I suggest uncompressing all files because 1. it’s easier for novices as only needs one command and 2. compression slows down file access times so may as well do them all now, including user profile, registry, system32 etc)

      But you’re right – just to get it booting up again you could do individual boot files, especially if really short of free space

  9. katy morris says:

    I am so so happy right now. After reading on boot manager compressed errors I was able to fix my laptop. Thanks a bunch.. I’d kiss ya if you were here. Lol. I was about in tears when another thing I read online didn’t work and I thought I’d lose a lot of files as only option on disk was to reinstall losing files and I haven’t backed up in awhile. :-] Lesson learned. A few of them. Don’t compress files (don’t need to) and backup more often.

  10. danilo says:

    it work for me.. thanks…

  11. Ruto says:

    I am so happy right now…..thought I would format the whole thing …Thanks

  12. bharadwaj says:

    thanks boss,your idea to BOOTMGR is compressed problem is solved but my windows 7 genuine copy is lost and it is showing ‘this copy of windows is not genuine’.that’s the only problem

  13. Ben says:

    Jesus Christ, Thanks Man..

    I nearly cried when I saw the message, now it´s fixed.

  14. Prashant shrivastav says:

    Thanks bro // its workin

  15. everen says:

    Help me if you are still there.
    I still have the problem .
    im using windows 7 basic
    my CD ROM is spoilt and cannot be used.
    Then I used up one pendrive to copy in windows 98 starts here to use my computer again.
    When I started. They say “no partiton table found. I cannot find any other way to boot it.
    I have the following things :
    Windows 7 all-in-one CD
    Windows xP home edition (genuine) CD
    Windows 98 /windows 98 starts here CD 194 mb
    a 16 GB / 4 GB/ *GB penrive
    Please save me. My computer is in a bad shape .
    Oh yeah, I acted stupid and compressed my ACER(C:/) but around 10 secs I canceled it. After that this problem showed up

    This is a repost. the old one has issues that can confuse you

    • Roy says:

      simplest answer is to just fit a new DVD drive? Or borrow a working DVD drive or use a USB portable DVD drive and un-compress with W7 DVD. Or take drive out and plug into another W7 PC and do it from there – it is also possible to create a W7 USB installation if you google for it (not easy)

      Depending how much damage has been done (W98?), if you have a backup you might end up having to reinstall W7 if de-compressing can’t repair it

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