Windows 10 AE, Microsoft Security Client Error code: 0x80070426

What a useless response. Instead of acknowledging the issue send people to a answer for a different OS that's 7 years out of date!

The first thing Syed N's articles  says to do is to make sure SLSVC is running by going to services - well it doesn't even list software licensing service on my machine (which is worrying).

And when will M$ fix the renaming a new folder takes two minutes issue instead of continuing to make out it's just a rebuild the index issue?

Highside, reading some of these responses is cringe. I have no idea how you aren't pulling your hair out. Just wanted to jump on this wagon and say I am having the same issue. Updated to windows 10 pro long ago (clean install). This started happening to me about a month ago. Same symptoms, nothing I have tried fixes it. Unlike you, I did not update my windows 10 edition. I have always been on the same windows 10 pro. I don't know what that means but seems to me that this problem could be on multiple versions of windows and be related to something common across versions?

Hello Steve,

To have a better view on this concern, may we know the following:

• Are you getting the error message when booting in Windows or when opening an application?
• What troubleshooting steps have you tried so far?

In the meantime, we suggest that you boot the computer in Safe Mode and check if you will still experience the same issue. Once done, perform a clean boot.

Let us know the result.

Hello Desiree,

Thanks for taking an interest in our problem.

Since Steve says his problem is the same as mine, I assume I can reply for both of us.

In any case, my problem is still there and here is some more information.

The Error dialog is shown after login. It pops up even if you do nothing at all after logging in.

When booting into safe mode, the Error dialog did not show, (but I note real-time anti-virus protection is unavailable in safe mode).

When performing a clean boot (all non-Microsoft services disabled), the Error dialog popped up just the same as before.

I tried an advanced reboot option that, from memory, was called something like "disable early start anti-malware protection". The Error dialog still popped up.

The problem is only there if I login immediately after reboot. If I leave the PC for a few minutes after a reset before logging in (just showing a very nice picture of some giraffes at the moment) then the Error dialog does not show.

While the Error Dialog is shown, its entry in the Taskbar shows the Windows Defender icon.

When the Error Dialog has popped up, the Windows Defender icon does not appear in the system tray until I manually start Windows Defender from the Start menu.

So this error does look like something to do with Defender is failing to start properly, which is worrying.

The most unusual things about my system are that it has 2 monitors and 3 HDDs, but I think that's common these days?

Any more suggestions?

Thanks for the sympathy!

It does look like a W10 problem to me, but for some reason only a small minority of PCs misbehave. 

I reboot so infrequently it is merely an irritation.

There must be a common factor. My misbehaving PC is nothing unusual. It has 2 monitors and 3 HDDs, but that's common I think, what about yours? Anything unusual about it?

Not really. I have a bunch of hard drives and two monitors like you. I keep it really clean, hardly any third party applications installed and I have steam and associated games on one of the other hard drives. Do any Microsoft techs or anyone at all know if windows defender has the ability to crank up the application logging output so we can see what is causing this error? My logs are bland right now. I found them in support. Just to be clear I don't mean the scan output logs I mean the actual application logs.

C:\ProgramData\Microsoft\Windows Defender\Support

Good Day All,

I had a the same problem occur this morning, same circumstances and same error code.  I have managed to get rid of it and fix Windows Defended start up.

I read through lots of posts until I came to this thread as I wasn't having any luck fixing it, until I read a post earlier in this thread where someone mentioned USB and the lightbulb went off.

Earlier this morning I installed Samsung Kies, Samsung Drivers for USB thingy and Samsung Safe Switch (something like that) for a phone I wanted to use I had hanging around.  Long story short, the software is pants and didn't work with the phone so I uninstalled Kies and SS being the junk they were, but figured I'd leave the drivers software as nothing wrong with extra drivers.  After this cleaned up registry as I always do after uninstalling programs and did restart, thats when the error started.  Long story short (I did lots of things that didn't work), I come to 5 minutes ago and the previously mentioned lightbulb moment, uninstalled the Samsung USB Drivers thingy and restarted, no errors and working Defender.

Sorry for the wall of text, and I'm guessing with the nature of PC's this might not fix all or any others, but I thought I'd share my experience of the error in the hope it might help at least one person.

Granted its only an error message that can be ignored and the program starts up later no problem, but thats not the way its supposed to work.

Have a good day,

Alex

Good Day All,

I had a the same problem occur this morning, same circumstances and same error code.  I have managed to get rid of it and fix Windows Defended start up.

I read through lots of posts until I came to this thread as I wasn't having any luck fixing it, until I read a post earlier in this thread where someone mentioned USB and the lightbulb went off.

Earlier this morning I installed Samsung Kies, Samsung Drivers for USB thingy and Samsung Safe Switch (something like that) for a phone I wanted to use I had hanging around.  Long story short, the software is pants and didn't work with the phone so I uninstalled Kies and SS being the junk they were, but figured I'd leave the drivers software as nothing wrong with extra drivers.  After this cleaned up registry as I always do after uninstalling programs and did restart, thats when the error started.  Long story short (I did lots of things that didn't work), I come to 5 minutes ago and the previously mentioned lightbulb moment, uninstalled the Samsung USB Drivers thingy and restarted, no errors and working Defender.

Sorry for the wall of text, and I'm guessing with the nature of PC's this might not fix all or any others, but I thought I'd share my experience of the error in the hope it might help at least one person.

Granted its only an error message that can be ignored and the program starts up later no problem, but thats not the way its supposed to work.

Have a good day,

Alex

Thank you so much for this very helpful info.

As for me on what it did the trick in getting rid of this error that just popped up out of nowhere last night I did the following.

So I myself own a Samsung On5 smartphone and I always hook it up to my PC to charge it or get music files to it, but never had an issue until last night, but I do want to say that I did try all the fixes all at once that were provided on this thread/others in doing all of the DISM.exe health/scan commands and the sfc/scannow and got zero errors on the console command, so I decided to uninstall the Samsung mobile USB drivers, plugged my USB phone cable from one port to another USB 2.0 port just in case, drivers got reinstalled and made a PC restart and voilá issue fixed! thanks to your problem findings which helped me to make the connection of this issue with the Samsung USB drivers and I hope this helps others out there. Still the Windows developing team need to work on this with the Samsung devs, make a fix on their end or something, so good luck to ya' all.