Windows 10: I can't update Windows Defender definitions

Hello, yesterday I have downloaded and run a program, which, I guess, have turned out to be a virus. There showed up a notification, that Windows Defender is turned off and I should turn if on. When I have clicked on this, Windows Defender Security Center showed up and there was written, that I don't have permissions to manage it or something like this and that I need to contact my administrator (I'm a private user and had had access to these functions before). Then I thought maybe it's a good idea to see what is changed on my disk after all and I have found out, that there were some files created in C:/Windows folder. I don't remember their names, but I deleted some of them.


And then my current problem has appeared. In Windows Defender Security Center (now I have all the permissions and don't need any administrator) it says, that I have old definitions (their version is 1.275.493.0, but their release date is 1.1.1970). When I click to check for updates, it looks for them for a few minutes and then nothing happens.


I have also tried manually downloading and installing current definitions from https://www.microsoft.com/en-us/wdsi/definitions, but when I run the executable, nothing happens as well.


How can I fix this?

:)

 

Windows Defender Definition Updates.

Thank you Elba for the prompt reply. However, there is a problem: In "Control Panel" under the "Programs and Features" page > "View Installed Updates" the " Windows Defender Definition Updates" are NOT listed. Consequently, I cannot delete/uninstall them.
The same thing happens when I use "Settings" >" Updates & Security" > "View Update History". Here the Definition Updates are all listed but I can't uninstall them either. Any other suggestions?

Thanks again, Fred

 

Task to auto update windows defender definitions disappears

My mom has a new laptop with windows 8.1, we always set the windows updates to manual.
On our other windows 8.1 computers I have created a task for auto updating windows defender definitions, which works fine for us.

This is how I created this task:

"Click on "Create Task", name it what you like (mine is Daily Signature Update), set the trigger as the time you want it to run every day.

For Action browse to Program Files\Windows Defender\MpCmdRun.exe and select it. In "Add arguments" add -SignatureUpdate -MMPC"

But somehow this task disappears once it has run on my mom's laptop.
I'm logged in as admin and then I also tried it with running the task scheduler as admin, the task just disappears every day for some reason, while it works fine on our other windows 8.1 computers.

Anyone an idea why this task disappears every time?

Thanks.

 

Definition Update for Windows Defender - KB2267602 (Definition 1.225.3124.0) - Error 0x80070643

Hello,

With the issue description, I understand that you are getting the error code for Windows Defender Error 0x80070643. I will certainly help you.

KB2267602 is the latest Definition update for Windows Defender. I would suggest you to follow the suggestion as a workaround given by
johnhawk88 replied on 24, 2015 and check if it helps.

Definition Update for Windows Defender - Error 0x80070643

If issue persists you may try the steps given below and check if it helps.

Method 1: Windows Update troubleshooter.

Run the Windows Update troubleshooter to try and fix the issue. Refer to the link to run the troubleshooter:

I request you to run the Windows Update Troubleshooter and check it helps.

• I search bar Type Troubleshooter and click on
  Troubleshooting;
• Click on the Find and Fix problems tile and then click on the
  view all button the left pane.
• Click on the Windows update
  troubleshooter and run it.

Method 2: Reset Windows Update components
and test the issue.

I suggest you to reset Windows Updates Components. Resetting Windows Update Components and the Windows Update files helps to fix Windows Update errors.

http://support.microsoft.com/kb/971058

Disclaimer: Important this section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow
these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs.

Backup the registry:
http://support.microsoft.com/kb/322756/en-us

Note: To reset the computer to normal mode after troubleshooting, please refer to “How to reset the computer to start as usual”
from the above article.



If the issue persists, I would suggest you to manually download the latest definition updates for Windows Defender.



How to manually download the latest definition updates for Windows Defender

http://support.microsoft.com/kb/923159

Hope this information helps. Please let us know if you need any other assistance with Windows in future. We will be happy to assist you.