Unable To Install Microsoft Security Essentials <Solved>

I’ve just spent the past hour or so fighting a co-worker’s personal computer, trying to get Microsoft Security Essentials to re-install (she had originally installed v1 of MSE, and when the v2 came out not too long ago and it attempted to upgrade, apparently it hosed her antivirus installation).  Her machine is running XP SP3 32-bit.

The original error code we received was 0x80070002 when trying to run the v2 installer.  I tried to run the v1 installer (downloaded from FileHippo.com), hoping to re-write whatever had become corrupted (as Add/Remove Programs didn’t show MSE as being installed at all).  However, that didn’t do anything, and it ended up failing to install as well.  From there, I went into Program Files and renamed the Microsoft Security Essentials folder so that the installation would be able to write to a fresh folder.  That didn’t work.  Then, I entered the Registry…

In the Registry, I searched for “Security Essentials” and proceeded to delete every KEY (which is the term for the folders) that contained any items referencing Security Essentials.  This took a while.  I re-ran the installation after that, to no avail.

I then went digging around the Application Data folder (C:\Documents and Settings\All Users\Application Data) and deleted the Microsoft Security Essentials folder and files.  I also went back into the Registry and searched for “Microsoft Antimalware” and again deleted every key containing items referencing the string I searched for.

At one point, after ripping enough items out of the registry, the error message I received changed.  It eventually  became 0x80070643, 0x80070648 and finally 0x80070645.  I then found a post that described two registry keys that could be causing problems (they appear to be telling the installer to upgrade rather than do a fresh install).  Once I removed these two keys and rebooted, all was well after re-attempting to install.  Below are the two keys I removed.

HKEY_CLASSES_ROOT > Installer > UpgradeCodes > 1F69ACF0D1CF2B7418F292F0E05EC20B

—Right click on1F69ACF0D1CF2B7418F292F0E05EC20B and delete the key

HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Windows > CurrentVersion > Installer > UpgradeCodes > 1F69ACF0D1CF2B7418F292F0E05EC20B

— Right click on1F69ACF0D1CF2B7418F292F0E05EC20B and delete the key.

I’m not sure if everything I did is necessary in order to achieve the desired results.  I’d recommend trying to remove the two last keys mentioned first, and if that doesn’t work, do everything else.  As always, keep in mind, removing information from the Registry is potentially dangerous to your system’s health, so make a backup of the Registry before proceeding.

12 thoughts on “Unable To Install Microsoft Security Essentials <Solved>”

  1. Thanks so much! Finally got it to install after 5 hours of Googling and troubleshooting! Your fix should be this first on the Google results!

  2. Thank You So Much, this worked for me, i had spent hours trying various uninstalls,
    Regedits, removing all old Folders e.g. AVG & Panda all to No avail.

    I Removed the Two Registry Upgrade items at the bottom of your post & Hey Presto, MSE Latest Version Installed OK after a Reboot.

  3. i am unable to find the keys in my registry editor, the program is not in my programs or program folder or registry key

    anything else you can give me for support ??

    computer is win 7 ultimate 64bit

  4. If you can’t find an entry with the same name, just export the whole keys to reg files, then the install should succeed. Afterwards, reinstall the keys by clicking on the saved reg files.

  5. Many suggested solutions recommend to delete


    But on current systems, there might be “Micosoft Security Essentials Client Update Package” installed. To reinstall MSE, after going through the usual MSE v2 removal instructions (http://support.microsoft.com/kb/2483120), also delete this key:


    (which contains 77B248F0AE65FAA42859180A2253B0E5)

    I figured this out using Process Monitor and setting a filter on HKEY_CLASSES_ROOT\Installer\UpgradeCodes\ registry accesses. I got the idea from http://blogs.technet.com/b/mark_russinovich/archive/2012/01/19/3476240.aspx

    1. Thank you! I can’t believe Microsoft can’t make this information available so people like us don’t have to spend DAYS hunting for it while our system is vulnerable!

  6. please help I don’t now how to get to the “HKEY_CLASSES_ROOT > Installer > UpgradeCodes > 1F69ACF0D1CF2B7418F292F0E05EC20B” to the “installer” & “upgrade codes” after I get into the registry. I am try to install MSE back on my laptop. gateway-nv52-refurbished-windows 7 64bit home version. all hell broke loose on my laptop when I open an email on 01/01/13.Thank you any help that you can provide. john

  7. I had a Trojan virus that hit with mse on. the mse support emailed me the viper cleaner but it still left registry “traces”,2 of them on the win7 system any help would be appreciated.

    1. I don’t quite understand the problem. It’s not terrible to have dead registry items that are benign. Are you just trying to clean up the registry or are you still infected?

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