error code 0xc8000408

Unable to update Microsoft Essentials Security.  Keeps coming up with error code 0xc8000408 and connectivity error.  I have uninstalled Macaffee, which I cannot stand to begin with, let too many things through even with updates.  Also checked Microsoft Defender, which is off.  I have tried to turn it on, but also get an error code.  I have a Dell Inspiron 1525 laptop with Windows Vista (another thing I hate).  I have checked other forums on this matter, hence uninstalling MacAfee and checking to make sure Defender is OFF.  ANY SOLUTIONS this is becoming frustrating.  I also have Comcast high speed internet if that helps also.

Question Info

Last updated March 9, 2019 Views 5,888 Applies to:

Hi Tina,


Is the issue with only MSE updates or with all types of updates (meaning Windows updates)?  Are you getting your normal Windows updates OK?  If you are having trouble with these other updates as well as MSE updates, then we need to reconsider the best options to pursue and you should post back.  If it is just MSE updates, then read on. 


I realize you've checked some of this, but included everything just to be sure (for example, just uninstalling McAfee isn't enough - you need to also use the McAfee removal tool as well or it will still cause you issues - and yes, that shouldn't be necessary but with almost all AV programs it is nonetheless).  And if using Vista, Defender can't just be off but it must be disabled (but perhaps that's what you meant when you said off).  The key here is that this can be the result of many different things and unless everything is checked and done properly, the troubleshooting may miss the critical item and thus make it seem like nothing is working when it's a simple oversight or a step was missed.


Please check out the following concerning update error codes in MSE:  Unfortunately, I can't find much about this particular error code - are you certain you've typed it exactly?  In your next reply, if the issue isn't resolved, could you please post the ENTIRE and EXACT error message word-for-word with all codes as that may provide additional help in identifying the problem.


Start with the following compliments of Dr. Strangelove (which is essentially an updated version of the link posted above based on the new version of MSE - but mostly the same otherwise):


Verify that you have removed all other real-time antimalware products that were ever installed on your PC, including free/trial products that were installed when the PC was purchased (Norton, McAfee, TM, AVG, OneCare, Malwarebytes (paid), etc). Then, use the cleanup tools here: List of anti-malware program cleanup/uninstall tools.  You MUST use the cleanup/removal tools to get rid of these programs properly as the normal uninstall process leaves remnants behind that cause problems with any other AV product you install later including MSE.


NOTE: If you have installed Adobe FLASH, and you already had the google toolbar, you were presented with the option to install “McAfee Security Scanner”, which is selected by default. If you were caught by this, and unknowingly/accidentally installed McAfee, uninstall it and use the McAfee cleanup tool in the list above.


Verify that your PC clock is correctly set. If not, correct it.


Verify that Windows Defender is uninstalled (if XP), or Disabled (if Vista/W7).


Verify that you are up-to-date with SERVICE PACKS and updates (including .NET and IE).


Yes, it can take some time to do this.


Remove Zone Alarm if you have it and use the Windows Firewall.


Verify that the Windows Firewall is on, and set to defaults.


Verify that you are not using a proxy server.


Verify that you have “install updates automatically” selected in Windows Update (even though the MSE definition updates are optional).


In IE, reset all security zones to default level.

Verify that you are using version 2.0.657.0 of MSE.


Then, restart your PC.




If that doesn't work, try the following:


Try a clean boot If the problem goes away then it's just a matter of tracking down the culprit causing the problem. Follow the procedures in the article. Once found, delete, remove, deactivate, or uninstall it. Once done be sure to reset Vista back to normal status as explained in the procedures. If the problem occurs in clean mode then just restore the system to normal status and reboot - this solution is not going to work.


Please also consider the following compliments of Stephen Boots - MVP:


First, see this -


Update FAQ -


You can manually download the (large file with engine and full defintions) latest definitions from the portal here:


If you are having problems with MSE not updating automatically or with the Update button -


What operating system and service pack?


Prior Security Software?


Any security software still installed?


A possible reason for this problem is that you have conflicting security software installed fully or partially on the PC. Remove all other security software from the PC.


You may need to use a cleanup tool to remove your prior security software:


Be sure to review this post: Check list for installing Microsoft Security Essentials




If that doesn't work, try uninstalling and re-installing MSE.


To uninstall MSE, proceed as follows:


To re-install, check out this article and follow the procedures: - but also check out the next paragraph before you begin the download.


If you do or ever did have any other AV program installed on your computer (even if you didn't use it), you need to make sure they are all uninstalled and fully removed before you install. To fully remove them, check out this listing of removal tools or the listing in that article at the bottom under troubleshooting steps (why this link isn't at the top near things to do first where it discusses removing all the prior and current AV programs is beyond me) or, if not on the lists, go to the website of the AV software and get and use the removal tool for that product.


To install, go to and click on languages and locales at the bottom of the Download button and then choose your language and the appropriate version for your operating system.  When you download, save it to the desktop (rather than running it).  When finished, right click on the installation icon and click run as Administrator (even if you’re logged in as an administrator) as I’ve found this sometimes helps.


Then configure the settings to your liking, update MSE (hopefully it will now work), and then run a quick scan (or a full scan if you have time) to get it started and reporting properly.




If the options presented don't solve the problem, you will have exhausted pretty much all of our tricks for resolving such problems and should submit a support case for free assistance from Microsoft with your problem starting here:


I hope this helps.


Good luck!

MVP(7/2012-6/2015),MCSE,MCSA,MCC2011,xCMM,xCAM,A+,Net+,Security Expert, xInfluencer. See Profile.

W10Prox64 Fast 16299rs3; Ofc Insider 1710/8613.1000; Edge,IE11,Chrome.

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