LandzDown Forum

Security => Security Software Programs => Topic started by: DR M on July 03, 2021, 08:03:56 AM

Title: Windows Defender scheduled scan
Post by: DR M on July 03, 2021, 08:03:56 AM
Hello.

Ever few days, Windows Defender gets that yellow warning triangle, that a scan is needed. Is there a way to do that by itself like Malwarebytes does every day?

Should I set it my self as a scheduled task or is there a setting I can enable for that?

Title: Re: Windows Defender scheduled scan
Post by: v_v on July 03, 2021, 11:28:54 AM
Panos,

Are you using Windows 10?  If so when you right click on the Windows Security icon on your taskbar and choose "View Security Dashboard", are all of the settings that you can find through the links on the dashboard set to "On"?  There are several categories of links there and all of mine are set to "On" and all of the scans happen automatically for me.  I never get that yellow triangle anymore nor do I have to do anything manually.

You can also get to the same pages by clicking the "Start" button, "Settings", "Windows Security", "Open Windows Security".

v_v
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 03, 2021, 01:40:32 PM
Quote
Ever few days, Windows Defender gets that yellow warning triangle, that a scan is needed.
I'm not getting these. The only time I see a warning that a scan is needed is when the computer has been turned off for several days and a scan has not been performed recently. Most notably I see this on my notebook because I don't use it often.

Microsoft Defender (formally Windows Defender) is designed to run when the computer is not being used or when you go idle. If you always turn off your computer when done using it, that may be part of the problem (though technically, telling you a scan is needed is NOT a problem). I just let mine go to sleep.

You can look in Task Scheduler to see when it is scheduled to scan. If no task is scheduled, it just scans based on the time it last scanned. If you set a schedule, it will scan at that time - unless you power off then it will attempt to scan when you come back.

My advice is to scan, then just let your computer go to sleep. Much happens to our computers when we are away - good things. Windows updates, housekeeping tasks (indexing, defragging and more) and our security programs (not just Defender) scan.

If you want to change the scan times and frequency, see How To Set Your Own Scan Schedule For Windows Defender Antivirus (https://helpdeskgeek.com/windows-10/how-to-set-your-own-scan-schedule-for-windows-defender-antivirus/) and scroll down to "Schedule Updates With Task Scheduler" (don't ask me why it says "updates". I think he meant to say "Scan times").

For the record, I recommend once daily scans though weekly is probably sufficient since Microsoft Defender is already scanning everything in real-time anyway.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 03, 2021, 03:18:18 PM
Hi, v_v and Digerati.

Yes, I use Windows 10, and everything is fine in the Security at a glance window.

The problem is that every few days I'm getting the yellow triangle warning about not a scheduled scan done.

Quote
You can look in Task Scheduler to see when it is scheduled to scan. If no task is scheduled, it just scans based on the time it last scanned. If you set a schedule, it will scan at that time - unless you power off then it will attempt to scan when you come back.

There was a scheduled scan for today, but no scan is performed while I am using the computer.

I always shut it down (not send it to sleep).

I created a new task for every Sunday and I will see what is going to happen tomorrow.
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 03, 2021, 03:31:35 PM
Quote
I always shut it down (not send it to sleep).

I created a new task for every Sunday and I will see what is going to happen tomorrow.
Well, just remember your computer has to be on (or at least in sleep mode) for the scan to happen. If you shut it down, you likely will see your yellow warning again. That is normal behavior.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 04, 2021, 10:08:01 AM
I don't think that the scan took place at all.

Although the Task Scheduler shows that the next scan is next Sunday, the Windows Defender status shows as last scan the one done yesterday.

The computer was on, and I was working on it.
Title: Re: Windows Defender scheduled scan
Post by: Pete! on July 04, 2021, 12:23:07 PM
I shut my computer down, and turn off the surge suppressor, when I'm not using it.

As far as I can tell anything scheduled during the night starts shortly after the next boot.

The only time I had to do manual scans in Defender, was when I was using Mcafee, or ESET, as my primary AV.

Possible factor: I currently have "Always register Malware Bytes in the Windows Security Center" turned off.
 
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 04, 2021, 01:22:23 PM
Quote
I don't think that the scan took place at all.

The computer was on, and I was working on it.
It is purposely designed to scan way way in the background so you don't notice it.

It is important to remember that these scan really are not necessary, except for peace of mind. This because Defender is constantly monitoring our systems 24/7/365, not just looking for malicious code being saved on our drives, but everything coming in and going out of our systems (emails, webpages, etc., and malicious behavior that might be going on in the computer's memory.

The fact of the matter is, these scans are redundant.

Go back to your Settings > Virus & threat protection page. It will show the last scan and type (I have mine set to quick). Then look down a bit to Virus & threat protection updates. Mine right now says last update was today at 8:49. am and that my "Security intelligence is up to date". If yours says the same (time might be different), then you are good to go.

Quote
Possible factor: I currently have "Always register Malware Bytes in the Windows Security Center" turned off.
Yes - this is what you want if you want both Malwarebytes and Microsoft Defender to run at the same time. I have the same setting set in my Malwarebytes control panel.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 04, 2021, 02:01:51 PM
Quote
Go back to your Settings > Virus & threat protection page. It will show the last scan and type (I have mine set to quick). Then look down a bit to Virus & threat protection updates. Mine right now says last update was today at 8:49. am and that my "Security intelligence is up to date". If yours says the same (time might be different), then you are good to go.

Security Intelligence is up to date here too. But as I said in my previous post, the last scan shown is the one I manually did yesterday.

Quote
The fact of the matter is, these scans are redundant.

I understand. But what bothers me is the yellow warning about WD needs my attention, and that a scheduled scan has to be done.

Quote
Possible factor: I currently have "Always register Malware Bytes in the Windows Security Center" turned off.
 

Sure. But it's not the case.
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 04, 2021, 02:43:20 PM
Are you saying you still have that yellow warning?
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 04, 2021, 02:45:40 PM
No.

But I will probably get it in a few days.  :)
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 04, 2021, 03:10:39 PM
Well, again, if you turn your computer off when done using it, that would be expected.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 04, 2021, 04:27:11 PM
In case that helps.

Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 04, 2021, 05:01:21 PM
Looks like it scanned to day and is scheduled to scan next Sunday. But again, it is running all the time and updates happen much more often than that - often several times a day, depending on what is happening out in the wild. I just checked again and another since my last post was released. Just another reason to let the computer go to sleep.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 04, 2021, 05:06:23 PM
Quote
Just another reason to let the computer go to sleep.

That means that I will have it on power all the time, since no battery available. I don't want that.

I'll try it however. It is something I would like to search about months now, I guess the time has come.
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 04, 2021, 09:01:34 PM
Quote
If you have multiple drives, my advice is to set Windows to create a PF on each drive and let Windows manage all of them.
Why? Is this a laptop with the battery removed?
Title: Re: Windows Defender scheduled scan
Post by: v_v on July 05, 2021, 04:41:02 AM
Panos,

Well I guess that I learned a little something today.  I could not figure out where you got the data in that little clip that you posted at "July 04, 2021, 12:27:11 PM".  Finally after a lot of internet searching I was able to find my version of that data.

As I mentioned in my earlier post I never get those little yellow triangles, and I do the same thing as you---meaning that I turn my computer off every night (or whenever I will not be using it for a long while) and unplug the power cords.

Having said that, when I compared my Task Scheduler data to yours it seems that the difference is that you seem to have set a schedule manually, whereas in my case I have not set a schedule (or a "trigger").  I have simply allowed Windows to do whatever it needs to do with Windows Defender.  (See my clip below)

So maybe if you delete the "trigger" for your "schedule" that you have set up for "13:00 every Sunday. . ." and just let the "trigger" stay blank perhaps Windows will just go about doing its business automatically and not bother you with the yellow triangles.  It is worth a try anyway.

v_v
Title: Re: Windows Defender scheduled scan
Post by: v_v on July 05, 2021, 03:10:28 PM
Panos,

Okay, after I had another night to sleep over it, if I try to integrate what Bill/Digerati said with my own comment the result might be the following:

 1.  Windows Defender is working all the time anywyay.  So it will run its scans when it needs to;

 2.  Therefore setting a scheduled scan is somewhat redundant as Bill/Digerati said;

 3.  It seems that a possible reason why you might be getting the yellow triangles is because you have set a scheduled scan with various "triggers", "conditions", and "settings" (see the tabs in your Task Scheduler);

 4.  The combination of your triggers, conditions, and settings may be blocking your "Scheduled Scan" when you are working at your computer and also when you turn it off;

 5.  If you wish to continue with your scheduled scans you can probably review and revise your triggers, conditions, and settings so that the scan happens in the background at various idle moments, while the computer is still in use;

 6.  If you get rid of your scheduled scan "trigger" altogether, then Windows will just go ahead and do what it automatically does anyway, which is to constantly work at 'defending' your computer.

So it would seem to me that either # 5 or # 6 should eliminate your problem with the yellow triangles, and if the Scheduled Scan trigger is redundant then why not just get rid of it altogether and let Windows Defender do its ongoing work?

v_v
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 05, 2021, 06:01:55 PM
v_v,

Thanks for that!

Quote
after I had another night to sleep over it...

As a matter of fact I created that scheduled scan after the default one didn't work (the day I posted about the issue here). Now, I deleted it.

I think that I won't do anything else, just waiting for a few days, if the warning appears again. If yes, I will post here with a screenshot.

If not, I will buy everyone here a coffee.  :D
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 06, 2021, 06:50:00 AM
Something changes.

See the today's attachment.

Title: Re: Windows Defender scheduled scan
Post by: plodr on July 06, 2021, 12:15:20 PM
That code tells you that either the scheduled scan could not be run (it was late at night so perhaps the computer was turned off) or the computer was not idle.
Thread explains what was said by Bill and v_v here
https://www.windows10forums.com/threads/windows-defender-error-code-0x8007042b.8895/

Make sure you have removed the scheduled scan you set up. In Defender be sure the scan is not set for a time when the computer is off.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 10, 2021, 03:24:52 PM
This is what I have today.

Before, I right click the scheduled task and chose Run, but after 3 hours the computer was working so hard so I ended it.

Title: Re: Windows Defender scheduled scan
Post by: winchester73 on July 10, 2021, 04:24:38 PM
Panos, when you open up Defender and click on Virus/Threat Protection, does it show a recent scan done under Current Threats?

Defender should be scanning all by itself without any human intervention or need to run on a defined schedule ...
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 10, 2021, 04:33:46 PM
Defender should be scanning all by itself without any human intervention or need to run on a defined schedule ...

Exactly. Mine, needs my intervention. I know that something is wrong, but I don't know how to fix it. I searched everywhere but I don't see something I have set wrong.

This is what is shown in Virus & Threat protection. It is the scan I manually did last Saturday, when I got the yellow triangle-warning.
Title: Re: Windows Defender scheduled scan
Post by: Corrine on July 10, 2021, 05:05:30 PM
1549950 files scanned!  No wonder it took so long to complete the scan.  The scan of my laptop took 58 seconds but that was for 40913 files.  Perhaps it is time to do a file cleanup, deleting unnecessary files and/or moving files not regularly used to a backup -- whether it be a USB or the cloud. 
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 10, 2021, 05:11:57 PM
Quote
1549950 files scanned!

I thought that was normal!

But indeed, it's ten years' work in there.
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 10, 2021, 05:44:47 PM
Well, this computer is 6 years old, but has nearly 20 years worth of data on it. I'm looking at a nearly 46,000 files taking 1m 21s.

While you are scanning 1.5 million files, it is still taking a long time. Is that a hard drive?

I agree with Corrine and you need to cleaning up, deleting duplicates, and moving some files.

Title: Re: Windows Defender scheduled scan
Post by: DR M on July 10, 2021, 06:07:55 PM
That's how I explain the "task can't be completed because the computer is not idle anymore" error. The computer can't be idle for so long.

The point is I don't have duplicate files and all are necessary for me there. Even though many of them will never be in use again. Yes, it's a hard drive. 1 T, and I have around 580GB free.
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 10, 2021, 06:32:24 PM
Quote
Even though many of them will never be in use again.
Then I would recommend you move them off to a couple back up drives. If they will never be used again, then don't need to be scanned over and over and over... and over again.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 11, 2021, 02:39:55 PM
Hi, All!

For some reason, my Windows Defender task has been fixed (I hope).

It's the first time I have these screens. And the files scanned? It says 14670! No idea why and how. I did nothing at all.

No clue about anything. It just happened and it happened for a FIRST TIME.

It seems that all these trial and error efforts were a shock to it! You know, like an ICD!  ;D
Title: Re: Windows Defender scheduled scan
Post by: v_v on July 12, 2021, 01:01:25 AM
Panos,

I am going to throw a wild guess out there about the "1549950 files scanned!" and the long time that it took to do those scans and why "after 3 hours the computer was working so hard" that you ended up turning the computer off.

I noticed that in the graphic that you posted on "July 10, 2021, 11:24:52 AM", the date in that graphic said "30/11/1999" for the "Last Run Time".  I thought that it looked weird at that time but since nobody else said anything about it I thought that it may not be relevant.  But now after all of the subsequent events it seems that it probably was really relevant.

Because neither Windows Defender nor Windows 10 were in existence in 1999 I am guessing that that date caused Windows Defender to do some sort of extraordinary scanning that it would not have otherwise done.  By that I mean that it probably searched every little item in the computer (or perhaps everything dated since 30/11/1999!).  That is probably how it came up with that huge number of "1549950 files scanned" in your post of "July 10, 2021, 12:33:46 PM".

Once Windows Defender had done this major scan my guess is that it did not need to scan every little thing anymore because it brought itself up to date so to speak.  Now, as your last post indicated, it can do the normal usual scan that all of us have usually experienced --- as your post said, "14670 files scanned" taking only "1 minute 58 seconds".  Based on most of the feedback in this thread this number of files and the time it took seem far more normal, and hopefully it will turn out to be that way for you going forward.

As to how that "Last Run Time" got to be "30/11/1999" I have no idea, although it might have had something to do with you deleting your previously scheduled scan.  Possibly the deletion did some sort of date re-setting back to that old date.  (Maybe some of the data in your Task Scheduler "History" tab might offer a clue.)

At any rate my conclusion is that Windows Defender should work much more normally for you now and everything should happen relatively automatically without your intervention, just like it does for the rest of us.

v_v
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 12, 2021, 09:56:21 AM
Quote
It is important to remember that these scan really are not necessary, except for peace of mind. This because Defender is constantly monitoring our systems 24/7/365, not just looking for malicious code being saved on our drives, but everything coming in and going out of our systems (emails, webpages, etc., and malicious behavior that might be going on in the computer's memory.

I really hope this is true. It is what we know, what we say, what we believe.

My Task Scheduler today is different. It shows the code 0x2, meaning that the scan log is not found. Although in the History below there is an indication that the task was completed, the Virus & Threat Protection board shows as last scan the one completed yesterday (https://www.landzdown.com/anti-spyware-software/windows-defender-scheduled-scan/msg204653/#msg204653).

Those screenshots in the link above are the ideal ones. They show that the scan is done/completed indeed. The point is that we don't get them, or at least we don't know when they appear. There are many people in the web asking about that 0x2 and it seems there is no clear answer on that.

I notice that v_v's screenshot has also the 0x2 code, so there is also a problem, in my opinion.

I am still watching the task. At least, it would be good to learn something more about it.
Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 12, 2021, 01:47:40 PM
Quote
I am guessing that that date caused Windows Defender to do some sort of extraordinary scanning that it would not have otherwise done.  By that I mean that it probably searched every little item in the computer

I think that is a decent guess, but I don't think that is it - but admittedly, I am working on a couple "guesses" too. I note 1999 is commonly used by BIOS makers as the default date (until the correct date and time is set in the BIOS Setup Menu). Note a totally inaccurate date and time is a common symptom of a weak/failing CMOS battery. The two primary functions of the CMOS battery is to (1) keep the "user changes" to the BIOS firmware default settings "alive" in the CMOS memory and (2) keep the motherboard's RTC (real time clock) "ticking" ("counting" to be more accurate) when the computer is turned off.

If the motherboard's CMOS battery has never been replaced on this older system, I would probably replace it. Typically they are CR2032 wafer or "coin" batteries, found at nearly every battery counter.

While I agree it "appears" Microsoft Defender (Windows Defender is its old name) did a deep scan, the screen shot says "Quick".

Also I just counted every file on my computer by opening an elevated cmd prompt, moving back to the root on the disk (cd .. until I got C:\> on the command line) on this system, and entering dir *.* /s. That lists every file and folder in that root directory and then the /s forces it to list every file in every subfolder on that drive too. In other words, every file on the disk. Even with a fast SSD, it took several minutes to list all the files on my boot drive.

And still I only(?) had 589,368 files on C drive. I did the same on my secondary drive and it only showed 13,485 files. That's 1/3 of the 1.5 million files you first displayed. Checking the other computers here, and all had fewer files than this, my primary computer.

Now why do I show ~600,000 on the disks but Defender only scanned 46,000? That's easy. Security programs, including Microsoft Defender know that only certain type of files are used by the bad guys. These typically are files that can be "run", otherwise known as "executables". This list (https://sensorstechforum.com/file-types-used-malware-2019/) is not all inclusive but gives you a pretty good idea of the most common file types used by bad guys to insert their malicious code.

By not scanning every single file on your disk, scans not only take up much less time, they also bog down our systems much less, and (especially for mechanical drives) result in much less wear and tear on the drives. Note since scans are "read" actions (not "write") the wear on SSDs is negligible.

Quote
I really hope this is true.
It is. EACH and EVERY file downloaded and saved on our systems ARE scanned on the way in by the real-time scanner. Every time a file is modified and saved to disk, it is scanned. Plus, when you call up any file, including one of those obscure file types, the real-time scanner looks for "suspicious" activity and will halt that activity if something fishy is detected.

Last but not least, regardless your primary scanner of choice, everyone should have a secondary scanner on hand for "on-demand" or supplemental scanning just to make sure we (users and ALWAYS weakest link in security) or our primary scanner didn't let something slip by. In other words, "for peace of mind" and I use and recommend Malwarebytes for that.

FTR, Malwarebytes has never, not once found anything malicious on any of my systems here going back to Windows 7 in 2009 with Microsoft Security Essentials (the W7 version of Windows Defender), through W8 and now with W10 and Microsoft Defender. That's a pretty good track record, if you ask me considering 2 of my computers are regularly used by guests, including several ("it can never happen to me") teenaged grandkids.

The only thing Malwarebytes has ever found on any of my systems are a couple "wanted" PUPs (potentially unwanted programs).

So keep your OS and your security programs current and don't be "click-happy" on unsolicited links, then chill. Odds of getting infected are very very slim.

Is it possible you can still be infected? Of course! It is possible Fort Knox might be robbed too. How? One of the guards opens the front door and invites the bad guys in. Or, a super-duper professional targets it specifically and manages to exploit some "unknown to everyone else" vulnerability.

The difference here is Fort Knox doesn't have backup copies of all the gold. But you, of course, have multiple current backup copies of all your data, including at least one copy maintained "off-site"! Right?
Title: Re: Windows Defender scheduled scan
Post by: v_v on July 12, 2021, 02:22:22 PM
Panos,

Here is another wild guess:  personally I would not get too concerned about a momentary instance of finding a "code 0x2" error in the task scheduler.  When I say momentary I mean that I can imagine that you might find a different value there at different times of the day.  When I saw that error in my own image that I posted previously I tried to do some research on it and found confusing and unclear results just like you did.  However my overall view and conclusion on the situation was simply that Windows Defender is doing its job, I occasionally get notifications from Windows Defender indicating that 'the scan were completed successfully and no problems were found', and thus I had nothing to be concerned about regardless of the "code 0x2" error.  To me it just seems to be one of the ways that Windows Defender goes about doing its tasks and recording the results, especially since it is constantly doing these tasks in the background.  Because Windows Defender will delay or postpone its tasks due to the lack of resources or intense user activity at any given moment it is possible that it will post such error codes or other messages.  Yet I do not think that these are indicative of problems.  They just seem to be indicative of temporary situations that occurred due to complications at that particular moment.

For example my task scheduler screen right this moment has the messages "The process terminated unexpectedly. (0x8007042B)" and also the code "(0x2)" error.  I will attribute these to the fact that I started using the computer in an intensive fashion around about that time and therefore interfered with Windows Defender's background operation.  To me this does not mean that there is a problem; it simply means that the background task is being delayed or postponed and that Windows Defender will come back to it later, when resources are available.

I am not a programmer and do not know how Windows Defender is designed to work in every instance, but in these cases I am willing to just "let go" and allow Windows Defender to do its work.  I guess as long as I see the "Status" as "Ready" and as long as I occasionally get the task completed successfully notifications with no problems found, then for me all is well.


[I just noted that Digerati/Bill posted an extensive comment while I was preparing mine.  What I have written above he reduced down to two words and a short sentence:  ". . . then chill. Odds of getting infected are very very slim."  Essentially that is the point of my post!]


v_v
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 13, 2021, 04:51:42 PM
Let me add my thoughts on the above.

1. The Virus & Threat Protection board shows two things:

2. From what I saw until now, the updates are daily, but the scan is probably set by default once a week.

3. The Task Scheduler may show the mentioned errors every day. When those errors are present in the Task Scheduler, there is no change in the Virus & Threat Protection board for the latest WD scan. So the errors regarding the scan are real errors.

4. When a week passes from the last WD update, it's time for the new scan to take place. So, no errors in the Task Scheduler anymore and the latest scan in the Virus & Protection board changes and gets updated.

I will watch WD's behaviour for a week more to see if the above apply to it. I don't doubt that everything is OK, but I want to know how my antivirus behaves. Not just say that it works. How it works? When the scan is taking place? Why those errors are present and when?

That's all for now.  :)

Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 13, 2021, 05:04:51 PM
Quote
From what I saw until now, the updates are daily, but the scan is probably set by default once a week.
The default scan is weekly but updates will occur at just about any time. I have seen multiple in a single day, and I have seen where nothing comes in a day. It just depends on what is happening out there in the wild. If a new vulnerability or exploit is discovered, MS will push out the update as soon as it is ready, even if another update came out just hours earlier. This is all good, IMO.
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 14, 2021, 07:34:27 PM
It seems that the default scan is not weekly!

This is my today's screenshots where everything continues to be fine:

Title: Re: Windows Defender scheduled scan
Post by: Digerati on July 14, 2021, 09:17:51 PM
There are other things that can trigger a scan (line some Defender engine updates) that may reset the schedule. In any case, I still would not worry about it - especially when no threats are found.
Title: Re: Windows Defender scheduled scan
Post by: v_v on July 14, 2021, 09:41:39 PM
Panos,

In my last post I wrote

Quote
However my overall view and conclusion on the situation was simply that Windows Defender is doing its job, I occasionally get notifications from Windows Defender indicating that 'the scan were completed successfully and no problems were found', and thus I had nothing to be concerned about regardless of the "code 0x2" error.  To me it just seems to be one of the ways that Windows Defender goes about doing its tasks and recording the results, especially since it is constantly doing these tasks in the background.

If as you wrote,

Quote
I don't doubt that everything is OK, but I want to know how my antivirus behaves. Not just say that it works. How it works? When the scan is taking place? Why those errors are present and when?

perhaps you might want to write to Microsoft for more details!  (Smile)

Digerati/Bill indicated that "The default scan is weekly" and despite what you experienced that may still be the case.  My understanding is that Windows Defender (WD) is constantly 'watching' things but 'watching' is not the same thing as 'scanning'.  It is quite possible that any behavior or experience that any of us may have could trigger off a 'scan' because WD was watching and decided that the circumstances presented a situation where a scan would be advisable.  There are probably a bunch of rules that would say something like "if this, then do that."  So again the best source for that would be the Microsoft programmers---and good luck with that!


[I see that Digerati/Bill has beat me to the punch again.  So I will repeat the two words and short sentence from his earlier post:  ". . . then chill. Odds of getting infected are very very slim."  To repeat from his most recent post this time, "In any case, I still would not worry about it - especially when no threats are found."]

So to me the point would be that the pursuit of knowledge about how WD works is laudable, but perhaps it is not worth the effort because only the programmers at Microsoft will know all the rules that they have set up.  Such a pursuit would then be more of a distraction from other more significant matters in life!

v_v
Title: Re: Windows Defender scheduled scan
Post by: DR M on July 19, 2021, 08:42:41 AM
The next successful scan was done yesterday, 18th July, 4 days after the previous one.

So it seems that everything is fine now, after a long time.

Regular scans, no yellow triangles/warnings, less files to scan, scan duration less than a minute up to 3 minutes.

So, no worries.  :)