Unable To Start the File System Shield. Shield Unreachable

My home computer uses Avast as its anti-virus software. Just today its icon on the tray sported a red X on its right bottom side indicating that it is not running. When I tried to run it, it showed the following message:

Unable to start the file system shield. Shield unreachable

Clicking on Start Scan kicks up another message:

Unable to start scan. There are no endpoints available from the endpoint mapper.”

Is this another trojan attack outcome? (Or, should I ask instead, am I getting paranoid?) My google search returned some results but I was never really given any answer as to how this happened – whether it’s caused by some freaking trojan or probably an unintended mistake my son committed in one of his computer adventures. Some of my research sources gave suggestions on how to correct the problem like the following:

  • Go to Control Panel and click on the Avast Entry in the Add/Remove Programs Window. Click ‘Change/Remove’ then choose ‘Repair’. Then reboot afterwards.

    While this may have worked for some, it didn’t in mine.

  • There’s also this solution in an avast forum that requires the use of some Norton tool. The procedure is rather complicated and the succeeding conversation between the problem solver and the user with the problem gets even more geeky and complex it gave me a headache. I am either not that tech savvy or just too lazy to do long procedures. Needless to say, I didn’t even try it.
  • The Avast Help Center. I clicked on its link on the upper right corner of the avast interface and a help app window appeared. Searching for the term “Shield Unreachable” returned a blaring ‘No topics found’ answer. I wasn’t surprised at all, because I knew how un-helpful most, if not all, Help apps actually are, especially (cough) Microsoft’s.

I however found an answer quite by accident. When I explored the Avast Interface (about 2.5 seconds before I would have thrown in the towel to give up), there was this sub menu under ‘Scan Computer’ that consists of ‘Scan Now’, ‘Boot-Time Scan’ and ‘Scan Logs’. The ‘Boot-Time Scan’ feature actually solved the “Unable to start the file system shield. Shield unreachable” problem. I believe this is not the perfect solution for this. There ought to be a better one out there and I might just have the motivation to find it should this problem arise again. But for now, this will have to do. After all, it worked.

The procedure is shown in the image below. My main purpose for doing this post is actually to serve as a reference for myself so that I wouldn’t have to search far should the problem present itself again in the future. I have posted a few articles of this sort here for the same purpose. If this helps others, good.


  1. Thanks for the help with the Avast Shield problem. Worked like a charm! Huzzah!

  2. tried your solution but when i clickrd on boot time scan
    it came up with only available in 32 bit and i am running
    in 64 bit got a solution for that one.

    1. Uh-oh. My home computer is 32 bit, and it’s kinda old. Had it been newer, I’d have installed AVG but since AVG complains about compatibility (with older computers) I had to settle with Avast.

      Is your installed Avast up to date? I mean, is it the latest version? I am not really very savvy about these things. As you can see in this post, my solution is something I found by accident and thought to share it to everyone who might find it helpful. I’m still in the process of searching for the best protection for my new laptop. I’ve narrowed my search down to Bit Defender and Kaspersky. As soon as I make up my mind between these two, I’ll immediately purchase a license.

  3. Nice post… Same thing happened to me and the first option (repairing trought the Windows Control Panel) worked to me and Avast is working nicely again.

  4. This happened to me as well, twice. The first time I uninstalled it and used a different product. I tried Avast again and after a couple days, same problem. After hours of frustration here is what finally fixed it for me. I went to control panel, programs, uninstall programs, clicked Avast, then clicked the update option. It downloaded and installed updates. Then I opened avast and clicked start program and all is well! 🙂

    1. also I just allowed Avast through my firewall and it was not on the list before. I don’t know if that had anything to do with it or not, but it can’t hurt!

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