Avast18.8 acting oddly

I use Avast18.8 for my WinXP and Vista builds. It is the final version for these operating systems.

For about the last month it has been acting oddly. AvastSvc.exe constantly uses high CPU. This makes the OS very sluggish. While Avast is starting up I get a screen saying I need to re-activate, then after a while longer I get ‘you are protected’

On other Avast versions, when you disable some or all the shields, AvastSvc uses less CPU resources. But not now with Avast18.8 I noticed AvBugReport.exe also running once, so I did a Repair. No change. What is running in the background with all the shields disabled?

My conclusion is sometime back there were some virus defs that Avast18.8 can’t handle (but are okay in later versions) that were put into a virus def update by mistake.

If I can find a Image Backup that I created from months ago, I’ll Restore it to verify that back then Avast18.8 worked without the AvastSvc.exe bug.

Check out this thread, particularly this post by avast staff. End of support for Windows XP/Vista - #317 by lukas.hasik

I just tested on XP virtual machine with Avast 18.8 and I don’t see such high CPU usage. VPS is 250204-6. Only difference I can see is that streaming update no longer works.

Thanks for the reply NON.

I have the same high AvastSvc CPU usage on both Vista and WinXP. These are two different machines.

I usually use vpsupd instead of online virus def updates. Did I use the wrong vpsupd sometime in the past? I download vpsuod for Avast24 and separately download the vpsupd for Avast12 thru Avast18

I’ll try some online updates to see if this clears up the problem.

Otherwise I guess I’ll have to do a reinstall, then do an online update to have the correct virus database

And yes Rocksteadym I know officially there is no support for Avast18.8 on WinXP and Vista

Hey DiehardWin98, I can actually reproduce, although on my 4c/4th the usage isn’t quite as high.
In my case we have the AvastSvc.exe process in which one thread is constantly locked at around 12% CPU usage in a 4c/4th configuration. This also makes csrss.exe (a Windows process) go high with around 9% CPU usage pretty much constantly. Something is definitely off as Avast has never acted like this before.

I’m talking about Avast 8.8.2356 build 18.8.4084.409 with the definition updates 250204-6.
The OS is Windows XP Professional x86 with all the Extended Support Updates up until 2019.

Well FranceBB, on my Vista build which uses a CoreDuo2 CPU at 2.1Ghz., Process Explorer shows AvastSvc using 77% CPU.

How much AvastSvc uses CPU resouces of course depends on the power and speed of the machine. But 77% definitely shows things down

My WinXP machine is Pentium4 at 2.8GHz. Things are really slow on this
OS with AvastSvc sometimes using 90% CPU

I continue to feel the problem is in the virus defs. Some defs that were probably for later Avast versions were added to the Avast12 thru 18 database.

I’ll do a clean install for Avast18.8 sometime soon. And to avoid the possibility that a wrong vpsupd caused the bug in the first place, I’ll do an online virus defs update. Then we’ll see if AvastSvc is still using high CPU.

well the point being that I’m seeing a grand total of around 24% wasted CPU usage for the same reason which is equal to around 96% if this was a monocore instead of a quad core, so yeah something is broken. The only reason why it’s less noticeable in a multi core processor is that avast is looping single threaded which means that the % is diluted when there are multiple cores but it’s a problem nonetheless. For reference, my normal usage used to be between 1% and 3%.

I think you’re probably right and some definitions were erroneously added and are causing some issues. I wrote an email to the support but I haven’t heard back from them yet. Perhaps it’s worth contacting them from your side as well. By the way, let me know how it goes when you reinstall.

@DiehardWin98 The forum is playing up badly this morning. I have inadvertently ended up replying to this thread elsewhere. So here is a link to that reply.

That’s fine if they’re gonna be relying on user feedback instead of testing them in their own environments, however I do actually expect them to fix them if they’re reported, especially for paid users. :slight_smile:

Let’s see how it goes, I haven’t heard anything so far, but it’s still early. I sent the email on Feb 4, 2025, 9:03 PM, so I don’t really expect an immediate response. Let’s see what they’re gonna say. Hopefully they’re gonna reply next week.

I reinstalled Avast18.8 on my Vista build. This didn’t go well. Uninstall was fine, but while reinstalling I got a BSOD and auto reboot. Then the OS was unbootable!

Usually before making any changes I create an Image backup, but not this time. I restored a 7 month old Image & copied the data from the defunct current build that I had saved before overwriting the partition.

On boot, Avast reported my license expired so I need to renew. I’ve posted on this boefore: When you select you want to renew Avast Free instead of upgrading nothing happens. So you have to reinstall to get another year’s worth of service.

I reinstalled. Then I did an online virus defs update. Avast also uploaded something: It was a new interface which makes Avast18.8 look the same as newer versions. I don’t know if that’s all that was uploaded

Each boot, when I check the status while Avast is loading, I get ‘need to reactivate’. Then fully 20 seconds later, ‘you are protected’ . So that’s 20 seconds with the OS unusable. This behavior is something recent, maybe the last month or so. That is, it was there in the defunct current build. Maybe I should have used the Avast Removal Tool before the reinstall?

AvastSvc seems to have calmed down. After initialize it uses much less CPU resources, down in the
10-20% range unless scanning.

Most likely, there were some virus defs updates that were bad recently and this was reflected in vpsupd. Goingfrom the 2018 database tdirectly to the current 250206-06 update skipped all the ones in between.

The BSOD I’m guessing is from the SSD. This is only 1 year old, and memory is Micron (not Chinese) so I would have expected better reliability. There wasn’t enough time to read the BSOD screen before the auto reboot happened

Actually, there may be paid users for Avast18.8. I read somewhere that ATMs still use WinXP. This was the reason for WinXP POS-Ready (embedded). POS is Point-of-sale. Somebody paid for that WinXP update after WinXP was officially dead.

After re-installing Avast18.8 yesterday, AvastSvc seemed to have calmed down

But, today AvastSvc is back to using high CPU. So, a bad virus defs update was NOT the bug.

There is a banner on the bottom of the Status page. ‘You have 10 secutiry issues’ and a button to Resolve. This brings up another screen saying ‘Lookining for issues’. On the bottom is a seccurity issues counter, another Resolve button, and $1.89/month in text (to update to Prenier). I ran this scan for 10 minutes and the count was still 0, not 10. So 10 is likely a bogus number to getyou to upgrade to Premier. There is no X to Exit, no – to Minimize. To exit you have to reboot, which I did.

So when Avast uploaded the new interface (skin), it lkely uploaded a search (data mining) routine. This is lwhat is causing the high AvastSvc CPU use in the background when no scans are running?

I said AvastSvc was using 90% CPU on my WinXP machine. If Premier uses this same search routine, why would anybody want to upgrade?

This AvastSvc using high CPU in the background issue is a big one that needs to be addressed. I hope FanceBB gets a reply from Support

I haven’t heard anything back as of yet. Anyway, I tried again to repeat the test running this time round in a VM using Virtualbox 7.1.7 r167389 and on top of the high CPU usage on csrss.exe and the AvastSvc.exe process itself, it seems to be causing issues with one of the threads created by the VBoxTray.exe process. What’s even more worrying is that I’ve set VBoxTray.exe in the exclusions as we can see here:


and yet, Avast is interfering with aswArPot.sys and aswSnx.sys being displayed in the stack trace even though they should be nowhere near the threads of that process:


Between AvastSvc.exe using resources itself and making csrss.exe and VBoxTray.exe go into an infinite loop, even in a 4c/4th configuration the overall CPU usage of the VM is 50% which is definitely not ok as it’s wasting half its power unnecessarily in what looks like an infinite loop.

This really needs to be investigated and addressed by Avast.
As for your question about Avast Premier, yes, I’m a paid user with Premier and I have the exact same issue with the Premier version:

I can also confirm that Streaming Updates no longer work in the Premier version of Avast 18.8.4084.409 either:

but luckily the normal scheduled updates kick in automatically, so all is fine, I guess, it’s just one feature less, I guess…

I finally got in touch with the avast support and it’s been one big disappointment.
I collected the logs with the old avastsupport.exe (given that the new one doesn’t work on XP) and sent them to Avast, however they stated that version 18.8.4084.409 is a build from November 15th 2018 and that although they’re still rolling out definition updates, they will not release any new updates to that version. From what they said, I can only assume that this means that any bug discovered will never be fixed and that essentially they don’t care about old operating systems like Windows XP any longer. I know that they stopped testing updates on Windows XP, but what’s the point of supporting version 18.8 and releasing definition updates if you’re not checking them to make sure they’re working and even when users report you the issues, you won’t do anything to fix them? I’m so disappointed with Avast right now, which is a shame, considering that I’ve been a user since the days of version 4.8…

That’s expected, as Windows XP is over 20 years old and its support from Microsoft ended more than 10 years ago. I would say it was quite generous for Avast to support XP for this long.

It’s time to move on… old PCs are like classic cars. Classic cars may still work on this age but it’s only for hobby; they cannot fulfill latest environmental or safety regulations. It’s the same for PCs; it may work but cannot have latest security measures.

Extended support updates ended in 2019, so it’s not that long ago. That being said, I’m not actually angry at Avast for the XP thing but rather for the fact that either a version is supported or it isn’t. Supporting a version means not introducing any new feature but still fixing bugs, not just rolling untested definitions updates and hoping for the best. Take Avast 4.8 for Windows 98SE for instance. It worked up until the very last definitions update in 2017 and I still have it installed in my machine.

Is it secure? Not even close, nobody would ever dream of browsing the web on Windows98SE these days, especially with outdated and vulnerable browsers (i.e retrozilla) and outdated antiviruses which haven’t been receiving definition updates for years (2,900 days have passed from March 3rd, 2017). Still, my point is that up until the end of support in 2017, it worked like a charm and it still very much does. The functionalities are there, it doesn’t hog up the CPU, the menus work etc. The point being that either they should deprecate version 18.8 entirely and call it a day or if they’re gonna support it they should be fixing bugs. That’s my 2¢ anyway.

One last screenshot, the last of the series.
Avast 18.8.4084.409 uninstalled and just like magic, Virtualbox started working properly.
No more infinite loops in VBoxTray.exe being stuck at 25%, no more csrss.exe going crazy, everything works as it should, thus confirming once again it was Avast all along…

I still use Avast4.8 on my Win98 machine and it works fine. I use Avast5.1 on my Win2K macchine and it too works fine. Of course, there are no new virus defs updatess. I don’t use VM. I’m just trying to keep these machines functional.

Yes, I am also diasappointed in Avast’s stance on Avast18.8. It worked fine until recently, so they made some changes that should be reversed. Apparently, it was not just a bad viirus defs update. I have been using Avast18.8 since I installed WinXP, so that’s over 15 years.

And it can contnue to work with a ‘simple’ reversal. I don’t recall ever seeing banners like ‘you have 10 security issues’ until recently, so Avast did some tweaks

FranceBB said Premier also has this issue. How can Avast justify selling Avast18.8 Premier if it is broken?

So NON, if you communicate to the developers that Avast18.8 Premier also has this issue, they will be compelled to act on it

By the way NON, you said you told the developers about vpsupd not working on Avast24.12. I had posted that Avast24.9 was the last version in which it worked. Any news on a fix?

Well, word meaning varies on people… in any case, “support” is ended already.

End of support for Windows XP/Vista

I believe these are just webpages implanted into GUI, so they didn’t modify programs but webpages.

Also, your screenshot shows Windows Embedded Standard… it’s technically a variant of XP, but I don’t think it’s not officially supported by Avast.

I don’t think so unfortunately…

Well, no news for fix… I got following response:

the vps update package is Instup compatible. There is no such functionality (now) for Icarus.

So, it means it won’t work from now on. They also stated that they might reconsider it if there is enough reason or mass demand for it.

NON, thanks for the reply

The screenshot is from FranceBB. I didn’t psrt any screenshots

Sorry, I should split reply.