2021-04 Cumulative Update for 2004/20H2 (KB5001330)

Well, here we go. Let’s see if the latest cumulative update still causes the performance hit or if it has the “fix” baked in.


Unfortunately yesterday I tried installing 2021-03 on my laptop and then applying the fix from MS/Epicor, as provided toward the end of this thread (Sudden drop Epicor speed caused by Microsoft Updates -> (KB4601319, KB5000802, KB5000808,KB4601382,KB4601383) + - #239 by aidacra) and it didn’t seem to be solving the performance hit for me. Job Entry still spinning and taking 6-10 seconds to load a job instead of 3-6 seconds, even after appying the local group policy and a reboot.

I installed the 2021-04 on my pc this morning and on one of the sales teams pc and noticed a great improvement in speed

I’ve installed it on my personal PC and my laptop, and in both cases it seems to have caused the return of the performance slowdown - 6-10 seconds to load/switch jobs in Job Entry. The good news is that it seems that applying the fix from Microsoft seems to be working effectively to resolve the performance hit now with 2021-04 (KB5001330) installed, on these two machines at least. Seemed to not work as well on 2021-03 cumulative update for whatever reason, but maybe I just needed two or three reboots for good measure. :man_shrugging:

Curious to know what others have experiencing with this update.

Installed KB5001330 on a few my work machines. All users reported slowness in Epicor. Applied fix to one of them mid-day yesterday and the slowness continued for that user. Waiting to hear back from the others later today but I have my concerns about this “magical” fix.

NOTE: Policy hadn’t been properly tweaked after the MSI fix was installed. Policy tweaked and waiting for feedback from the user reporting slowness.

The fix worked on one computer that I tried it on. They hadn’t gotten the KB5001330 update though.

Chiming in on this too - applied the H2 update, then the group policy ‘fix’ from support/Microsoft and saw a decrease in quote/job/order loading times by 75%. (took 10 seconds before, takes 3 seconds now). We’re going to roll this out to a few of the folks here today and I’ll report back if anything goes awry.


I never applied any of the original patches to my computer, but when I did the updates yesterday (H2) I got the KB5001330. It killed my performance. Unfortunately I did it right before a training session :crazy_face:. I then applied the temporary fix and it’s much better.


We have been letting the 2021-04 Cumulative update roll out (mostly KB5001330 for us, since we have almost entirely Windows 10 2004/20H2 clients), and are having good luck now with the Microsoft fix provided by Epicor resolving the performance issues. One thing we had to add to our deployment powershell script - our script both sets the Local Group Policy object like Epicor instructions inform you to, and it also sets the HKLM registry keys.

In case this comes in useful for anyhow, here is the PowerShell script that is run after the MSI file is installed for us. NOTE: this only works for Windows 10 2004/20H2 at the moment, but could be easily modified to apply the GP/registry fix for the other versions of Windows 10 if you have some of that in your environment.


1 Like

Further to my comments above

On my PC I have winver 20H2, before the 2021-04 Cumulative update I had installed the KB rollback fix which had little effect, and after the 2021-04 update the performance was a lot better

The other user that I tried the 2021-04 Cumulative update on has winver 1901, when they did the update the performance improved a lot (without the KB Rollback)

Another user with winver 20H2 did the 2021-04 Cumulative update without the KB rollback and the performance is worse

1 Like

What is this ‘fix’ you are talking about? I can’t get to the Epiccare article even though I have a login. It says no article found.

I want to see if it helps us. I am having the slowness issue as well as some of our users. I do have the 2021-04 installed



If that doesn’t work, maybe you can just login to EpicCare and search for the article?

Should show up under KB0110540


Can’t get to it - not sure why this is so difficult for me

If you haven’t accessed it yet, make sure you’re logged in before trying to access the link. It really should let you know that you can’t access it because you aren’t logged in.

I sent you a private message @jimship

Interesting update on one of Epicor’s KB articles: ERP 10 - February and March 2021 Windows Updates Causing Performance Issues - Knowledge Portal (service-now.com)

It looks like this whole issue is related to Epicor Themes. If you have a “bad patch” installed and disable theming there is a night and day performance boost.

I have been implementing the fix that was provided by Epicor and Microsoft. Most of the time it fixes the issue but on a few it make no difference at all.

Has anyone else had the same experience?


You are a thorough guy so you may have already tried this, but I made the mistake of applying the fix and assuming it didn’t work only to find out that it wasn’t the fix that was slowing the user down… it was a personalization. So I purged their personalization, cleared the cache and then it started working fine.

Did you already try the personalization purge for them and the clear cache @jdewitt6029 ?

@jdewitt6029 - this was my experience on a few workstations, but usually if the fix “didn’t work” I just needed to edit the local group policy, and the registry key, one more time, apply, reboot, and then it works. Not sure why sometimes it seemed to just now work the first deployment.

1 Like

@utaylor , did that and it made no difference.
@Noffie , Did that too and it made no difference.

I don’t know what it is about today but i have tried the fix on 4 stations today and all 4 the fix did nothing. When i open Quote Entry and try and drag it across screens, it lags way behind the mouse.