Boot manager failed to find OS loader 0x490

October 22, 2010 6:11 pm by

Background to the near catastrophic event

Last night, I was modding my Motorola Droid with this sick theme called DarkEdge, to prepare to sell it to a lucky buyer.  In order to remove my Google account from the phone, however, required me to factory reset the phone.  Well, that turned out to not be a good idea because DarkEdge tampers with several files that custom ROMs normally don’t touch [since DarkTheme is also a skin, not just a custom ROM], and as a result, I was stuck in a force-close loop.  Luckily, I can still turn on USB storage so I thought that to solve this simple problem would be as simple as downloading an file and booting into recovery to flash the firmware.  However, all the different ones I tried [FRG22d, CM 6.0, etc.] all failed the signature check, so the only way to go from here is to flash a .sbf file, which I have yet to do.

Catastrophic event

That was the background to what I’m really getting to because downloading all those files from around the internets caused Microsoft Security Essentials to raise a flag that it detected a trojan on my computer!  I have never gotten viruses/trojans/worms before [at least, not that I have noticed :P], so when I was reading the description of this trojan, my computer suddenly shut down for no reason!  When I tried to boot up again, it went straight into the Windows 7 Recovery Mode.  It ran an automated startup repair, which I thought, OK good..usually this will just fix the boot sector or MBR and I’ll be on my merry way.  However, this time around it threw the error “Boot manager failed to find OS loader” with “Error Code = 0x490”.  Thus, when it restarted I was just brought back into the System Recovery Mode, and it did the same exact thing.  Over, and over.

Side note: I divided my HDDs into three partitions: OS, Applications, and Data.  I knew that in the event of catastrophic failure of the OS, setting up these partitions will allow me to retain my data if I have to reformat.  However, what I never knew was if I were to re-install the OS would I be able to not have to re-install all my applications.  If someone knows, please do tell.

I started freaking out because I never had this problem before, and I did not want to reinstall all 100 [exact, yes for real] applications that I have on my desktop.  System restore also did not work.  So, I opened up my laptop and began to search for answers online using my strong google-fu.  After trying multiple solutions, some of which are bogus, I finally found the correct one that allowed me to type this up on my desktop.  I am writing this down for posterity and to hopefully have this correct solution reach out to more folks who are suffering the same problem.  I will definitely be more vigilant with my backups and system recovery images from now on.


This is the link to the thread I found the answers, for reference and citation.  Kudos to momominimo.

If you don’t have your Windows installation disc:

  • Try and cancel the automated startup repair, once you get it to stop, click the link to go to more advanced diagnostics and repair
  • Choose your language
  • You will have to sign in to an account on the computer to verify ownership.
  • Select the option to open up a command prompt
  • You will be running bootrec.exe along with some options, which will depend on your situation.
  • Take a look at the different options below you can run with bootrec.exe to determine which ones you might need to run
  • For me, I ran “bootrec.exe /fixmbr” (without quotes), which you should then see a success message, and then “bootrec.exe /fixboot” (without quotes), which you should see a success message as well.
  • Once done, type the word “exit”, and restart.
  • Hopefully it should boot up now 🙂
  • If you do have your Windows installation disc: (from hereon copy and pasted from source)

  • Put the Windows Vista or Windows 7 installation disc in the disc drive, and then start the computer.
  • Press a key when you are prompted.
  • Select a language, a time, a currency, a keyboard or an input method, and then click Next.
  • Click Repair your computer.
  • Click the operating system that you want to repair, and then click Next.
  • In the System Recovery Options dialog box, click Command Prompt.
  • Type “Bootrec.exe” (without quotes) along with the option that you want to run, and then press ENTER.
  • The commands I ran were (without quotes) “bootrec.exe /fixmbr”, and “bootrec.exe /fixboot”.
  • Type the word “exit” and restart.
  • Bootrec.exe Options


    The /FixMbr option writes a Windows 7 or Windows Vista-compatible MBR to the system partition. This option does not overwrite the existing partition table. Use this option when you must resolve MBR corruption issues, or when you have to remove non-standard code from the MBR.


    The /FixBoot option writes a new boot sector to the system partition by using a boot sector that is compatible with Windows Vista or Windows 7. Use this option if one of the following conditions is true:

    • The boot sector has been replaced with a non-standard Windows Vista or Windows 7 boot sector.
    • The boot sector is damaged.
    • An earlier Windows operating system has been installed after Windows Vista or Windows 7 was installed. In this scenario, the computer starts by using Windows NT Loader (NTLDR) instead of Windows Boot Manager (Bootmgr.exe).


    The /ScanOs option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option displays the entries that are currently not in the BCD store. Use this option when there are Windows Vista or Windows 7 installations that the Boot Manager menu does not list.


    The /RebuildBcd option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option lets you select the installations that you want to add to the BCD store. Use this option when you must completely rebuild the BCD.

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    Jesse is a software engineer at Facebook, who just graduated from UC Berkeley. Passionate about mobile technology and entrepreneurship, he started his own blog as a home for his tutorials, projects, and random thoughts. Follow him on Facebook to stay updated on his latest tutorials and projects.


    1. yes, exactly

      Comment by Jeff Ho — October 23, 2010 @ 7:13 AM

    2. yesh! 😀 thanx! :D:D:D:D:D

      Comment by Jared — December 31, 2011 @ 7:35 AM

    3. You are my Hero! I had the Geek Squad and several Geek friends tell me it couldn’t be done! I am SOOOOOO grateful! 🙂

      Comment by Lorna — March 18, 2012 @ 1:16 PM

    4. Thanks…It help me a lot!!

      Comment by Anonymous — December 9, 2012 @ 12:57 AM

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