Hello:
You need your software updater to check for ESET before trying to push a Defender update. ESET disables defender and the installation will fail every time.
Since Microsoft Defender is correctly asleep while ESET is on duty, the Error Code: 4 panel belongs entirely to CCleaner’s background Software Updater engine.
Thank you!
Defender turns itself off when you install/enable any 3rd party AV.
(ESET does not “disable” Defender; Windows turns Defender off when it sees a 3rd party AV is enabled).
However even though Defender is not running Windows Update still updates Defender and it’s definitions.
This is done for two reasons:
And that is why CCleaner also offers Defender updates even when you don’t have defender running as your real-time AV.
As you note Error Code 4 is a CCleaner error code.
They don’t publish them, so I’m not sure what it means, but it isn’t because you have ESET.
PS. I personally do not believe that CCleaner should be offering any Windows Updates - Windows itself takes care of them as and when needed.
I suggest that you ignore them (untick them) when CCleaner offers them to you. That’s what I do.
Hi @Radon82,
We will be releasing CCleaner v7.9 soon. When this is available, please update and let me know if you are still experiencing this issue.
@nukecad v7.9 will have an option to ignore a currently offered update or skip all update offers, so you will no longer need to untick them, you can just set them to skip.
Hello sir, I was able to hide these issues with the new version. I really like this feature. Also just sharing the fact that this occurs. If there is another way to submit a suggestion or just share info let me know.
Thank you!
Yes, I fully agree on the windows updates and the more specific wording would be as my original research returned before short handing it 
When installing a third-party antivirus like ESET, Windows automatically disables Microsoft Defender’s real-time protection and background scanning to prevent system performance issues and software conflicts.
Microsoft Defender will not perform regular scans by default if you have ESET installed, unless you explicitly choose to turn that setting on.
However, Windows includes a feature called “Limited Periodic Scanning”. If you choose to manually toggle this setting on, Defender will stay up to date and run occasional background scans alongside ESET.
Primarily Windows keeps Defender and it’s detection definitions up to date even if you are using a 3rd party AV, so that if you do stop using that AV then Defender can take over straight away without having to load all the updates since you started using the 3rd party AV.
Windows 11 Pro 25H2 disabled “Limited Periodic Scanning” as well as the real time protection by default upon installation of ESET, hence the need for the update called out by CCleaner. That is why I was making the comment, if it was something that I chose to shut off, I get it. Not sure what OS you are using. As you can see from Microsoft’s official documentation the verbiage, “can be enabled is used.”
Even with periodic scanning disabled Windows will still keep Defender and it’s definitions updated.
It doesn’t on my machine where I have a 3rd party av.
About once a month or so I turn off my av and Defender takes over and I select to update it. It starts updating and I can see also the last time it updated. (about a month ago)
All I can say is that from all that I have read WD should be updating even if you are using a 3rd party AV.
(You shouldn’t need to DIY).
That’s so its’ up to date if you ever want to run a manual scan (of a single file from the right-click menu, or of the whole system), or if you want to disable/uninstall your 3rd party AV.
Otherwise it would have to take time to update if/when you use it for a scan, or if you disable/uninstall the other AV.
@hazelnut What happens if it’s been a while since you last updated it, and then you right-click a file and select ‘Scan with Microsoft Defender’ from the context menu? (You’ll need to use ‘Show more options’ in Win11).
Does it then update before scanning, or does it scan using the out-of-date definitions?
This is on a Win 10 machine.
No ‘scan with Windows Defender’ in context menu, only ‘scan with my 3rd party av’.
Always been that way.
Turned my av off just for you, last definition update was 22nd June and I did the monthly platform update as well to make it all the same.
It now shows
Version: 1.453.404.0
Engine Version: 1.1.26050.11
Platform Version: 4.18.26050.15
Released: 7/3/2026 9:32:53 AM
Documentation: Release notes
and will stay like that until I manually update again.
By the way, I don’t need to do the ‘show more options’ thing on Win 11, I just use the accepted workaround to show everything as it was before.
First off Thank you to @nukecad and @hazelnut. As we can see Defender has different behaviors in different scenarios. The real kicker is that CCleaner does not have the correct permissions to update the files while 3rd party AV has it in sleep mode. That was the original issue with the Code 4. The new option given by @Laurence_CCleaner is fantastic, it is like pinning an update in PowerShell hence giving the GUI the same benefit as a power user.
Winget upgrade --all --include-unknown
Name Id Version Available Source
WinDbg Microsoft.WinDbg 1.2603.20001.0 1.2606.22001.0 winget
1 upgrades available.
1 package(s) have pins that prevent upgrade. Use the ‘winget pin’ command to view and edit pins. Using the ‘–include-pinned’ argument may show more results.
(1/1) Found WinDbg [Microsoft.WinDbg] Version 1.2606.22001.0
This application is licensed to you by its owner.
Microsoft is not responsible for, nor does it grant any licenses to, third-party packages.
Successfully verified installer hash
Starting package install…
██████████████████████▊ 76%
Yes every computer is a bit different, they are “Personal computers” after all.
The ability to skip/ignore software updates in CCleaner, the same way that you can skip/ignore driver updates, is something that we have been asking for for a long time now.
So it’s good to see it finally implemented.
@hazelnut It’s not important but I’m wondering if your context menu tweak is why you don’t see ‘Scan with Defender’?
I have both ‘Scan with Defender’ and ‘Scan with Malwarebytes’ on my context menus. (both Win10 and Win11).
The context menu tweak is for Win 11 only.
‘Show more Options’ doesn’t happen on Win 10.
Most full av’s turn off Defender when installed, perhaps it’s possible to run Defender and MBM at the same time which is not possible with a full AV and that is why you have both in your context menu.
Yes Malwarebytes and Defender can run at the same time.
It isn’t something that you should normally do with 2 AV’s because they will interfere with each other.
But Malwarebytes works in a different way to “usual” AV’s so it gives you an option to run both side by side for an extra layer of protection.
(Not just Defender, it can also run safely side by side with other AV’s).
TBH though I only run Defender real time, I have Malwarebytes Free version there for manual scans to give a second opinion.
(I also use Malwarebytes Browser Guard add-on to give an extra protection layer in my browsers).
