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Apparent Win10 Defender Update Issues Illusory

Over the past week to ten days, lots of users have been reporting issues with Windows Update and Windows Defender. This applies to versions 1607 (Current Branch) and 1703 (Insider Preview aka Creators Update). The symptom is that while Windows Update reports a Definition Update for Defender is available, it cannot download or install same. As it turns out, these apparent Win10 Defender update issues are illusory. In fact, they’re easily addressed with a simple fix. One need only use Defender itself to grab its own updates, and the issue vanishes. Here’s what Windows Update reports when this error occurs:


The consistent thread for both 1607 and 1703 versions is error code 0x80070643 for this particular problem.

Normally, when Windows Update (WU) goes wonky, recovery requires troubleshooting. This usually starts with the “Fix problems with Windows Update” item available in the Troubleshooting widget from Control Panel. But for this particular issue, no such shenanigans apply. On version 1607, launch Windows Defender, click the Update tab, then click “Update definitions.” For version 1703, visit Windows Defender Security Center. Click the “Virus & threat protection” icon (third item from the top in the left-hand icons), then click “Protection updates.” Either way, this launches a manual update download outside the Windows Update umbrella.

Fix Step 1: Addressing Apparent Win10 Defender Update Issues

def-error2 In 1703, clicking “Protection updates” produces this screen. Next, please click the “Check for updates” button at the bottom. This tells Defender to poll the server for updates, and to download and install any available updates it finds. The mechanism is independent enough of WU that it will work even when WU won’t.

Fix Step 2: Addressing Apparent Win10 Defender Update Issues


Something is obviously up with Defender update handling, because this also produces an error message as well, as shown here. Don’t let this trouble you. Although it says “fatal error,” indeed the update is working in the background to download and install the necessary malware definitions.

Fix Step 3: Addressing Apparent Win10 Defender Update Issues

def-error4Click the “Protection Updates” button again. The result is a successful download and install of the previously failed update (same version number as before 1.239.778.0). Wait a minute (60 seconds) before you do this or you’ll get an error message that says “You must wait for the previous update to complete …” But indeed it will proceed and complete successfully.

Fix Step 4: Addressing Apparent Win10 Defender Update Issues

Now, you can close Defender. If you return to WU, and ask for updates once again, you’ll get this “all clear” response instead. Problem solved!

Microsoft hasn’t yet explained what’s causing this issue, nor have they released a fix for it, either. I’m hopeful that it will be history by the time that April 11 rolls around to mark the official release date for Creators Update. We’ll see…