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Can confirm the same on my 2013 MBP (15" retina) with 10.15.5 - Kernel panics and restarts every few minutes.

I don't have an external monitor or a dock plugged in, and I tried disabling nap, sleep and all of the above suggestions - none of them really helped.
Sometimes it could go half an hour or so without a restart, or it could restart every 5 minutes - there didn't seem to be much logic to it other than high load on the WindowServer process just before restart.

In the end downgrading to 10.15.4, using the gibMacOS tool, solved it. Building a full installer and running it downgraded with no issues, and retained all apps, settings and data.

I've been running 10.15.4 for a while and the crashes were still present, but perhaps once every two days rather than every 5 minutes.
After reading something on the forum about upgrading a second time not causing the issue, I upgraded back to 10.15.5 using the automatic updater - not had a crash in about a week of constant usage so far (touch wood)
 
Installing 10.15.6 (non-beta) via the combo update has not fixed the powerplay panics for me.

now trying a full install via usb disc. Not holding out much hope...
 
Update from me, 4 days without panics/freezing since deleting ALL 32-Bit-apps and some malware (myupdate...)
 
Same thing here with the new 10.15.6 update.
I did and tried every possible fixes.
Do we know if Apple are still working on Catalina or do I really have to re install Mojave?
(Since my iMac doesn't support Big Sur, and since I don't trust Apple anymore).
 
No more kernel panics for me too so far. Had the issue that my MBP 16 crashed whenever it went to sleep with an external monitor in clamshell mode. I hope that the issue now has been permanently fixed for my use case.
 
Hooray! 10.15.6 fixed the consistent kernel panic crashes when trying to resume from sleep with an external display connected and the lid closed in clamshell mode on my 2019 16" MBP. Good job Apple.
 
Same thing here with the new 10.15.6 update.
I did and tried every possible fixes.
Do we know if Apple are still working on Catalina or do I really have to re install Mojave?
(Since my iMac doesn't support Big Sur, and since I don't trust Apple anymore).

One thing you could try is create a new Container partition on your internal drive and clean install 10.15.6 to the new partition. Reboot to the new partition and see if that helps.
 
One thing you could try is create a new Container partition on your internal drive and clean install 10.15.6 to the new partition. Reboot to the new partition and see if that helps.

I think I'll try a full Catalina reinstall without migrating the settings.
I've been upgrading systems over each others with migration for years now, maybe a fresh starts will fix it.
 
With 10.15.6 it got better, but it didn’t solve the issues completely. Crashes after sleep in clamshell do now not occur every time, as before, but every 4th or 5th time.
 
Interesting that 10.15.6 seems to gave fixed it for some, but not for others. 🤔
Please remember that bugs don't appear every time. Every restore/update may or may not repair your system. That's why we can't be sure that every logic board replacement is a solution. In some cases it could be hardware problem but also it could be just about system reinstall.
 
Since I upgraded to 10.15.6 I'm getting these kernel panic crashes a couple of times per day. 2018 Mac Mini connected to a Samsung Frame TV.
 
Update from me: MBA changed the freezing to a short freezing period (1min), after cleaning dust from inside... no crashing so far
 
I have this problem constantly on my Mac Mini (2014) since the newest OS update. It is preceded by frantic writing to external USB backup disks (writing what I do not know) and the screen brightness flickering. I get the "unrecoverable security agent keychain" error message box, followed by a freeze and eventual crash. I am not viewing videos at the time but VMWare Fusion running Windows 10 is always running when this happens. This happens several times daily.
 
I have this problem constantly on my Mac Mini (2014) since the newest OS update. It is preceded by frantic writing to external USB backup disks (writing what I do not know) and the screen brightness flickering. I get the "unrecoverable security agent keychain" error message box, followed by a freeze and eventual crash. I am not viewing videos at the time but VMWare Fusion running Windows 10 is always running when this happens. This happens several times daily.

What does the Console log show for the reason of the crash? It sounds like the crash you are experiencing is different then the ones reported in this thread.
 
I think I'll try a full Catalina reinstall without migrating the settings.
I've been upgrading systems over each others with migration for years now, maybe a fresh starts will fix it.

Ok I did a full clean reinstall (without migration assistant), it seems to have fixed my problems.
Maybe all those problems have something to do with migrating systems from ages?
 
The problem didn't start until after the 10.15.6 update.

System Software Overview:

System Version: macOS 10.15.6 (19G73)
Kernel Version: Darwin 19.6.0
Boot Volume: Macintosh HD
Boot Mode: Normal
Computer Name: Dave's iMac
User Name: Dave (dave)
Secure Virtual Memory: Enabled
System Integrity Protection: Enabled
Time since boot: 41 minutes

iMac (Retina 5K, 27-inch, 2017) - Technical Specifications

It's an older iMac, and I thought maybe the hard drive was just getting old, but I can't verify that, and the error message after the forced reboot >:-( doesn't seem to justify a forced reboot. If the issue is the age of the iMac and some sort of incompatibility with the latest software (that I'm constantly prompted to install from Apple, with no choice to disable that prompting), then maybe Apple needs to consider that people won't like the idea of forking out $3K every 2 years, on newer computers that don't show any performance benefit for the software we're using, just to prevent random forced restarts... which didn't happen before Catalina.

Here's the important error message I guess:

"userspace watchdog timeout: no successful checkins from com.apple.WindowServer 120"

The forced restart happened after I left work last evening and before I got here this morning. I simply clicked to go to the login screen last evening. I'm not sure if the iMac goes to sleep during that time, but I've also attached any relevant sleep settings I could find. I'd prefer it go to sleep after say an hour or two of no usage or being on the login screen, but I don't see fine-tuning in that area like I do on Windows.
 

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Please remember that bugs don't appear every time. Every restore/update may or may not repair your system. That's why we can't be sure that every logic board replacement is a solution. In some cases it could be hardware problem but also it could be just about system reinstall.
You're right, of course. It's just that this problem is so difficult to get a grasp on. First it seems it was only related to newer graphics cards from AMD, but then people with Intel graphics started to report about the problem.

A user over at Apple Discussions is reporting that a motherboard replacement has fixed the problem on his MBP 16". Another that a clean install of 10.15.6 helped. But there are also users which didn't get better results from a clean install. Hmm....
 
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I think there are at least 2 separate problems here.

1) The “resume from sleep” issue (I.e. people that just have that issue) and
2) that issue, plus other issues, particularly panic during startup issues.

Issue 1 seems to be the one where people get a resolution via power settings changes or software installs or clean installs of 10.15.6.

For people that have that issue plus other issues, particularly startup issues, my view is that hardware issues may well be the cause.

Eventually I convinced Apple support of the distinction (initially they tried to stick to the “software issue” response, but after I completed a clean formatted install with them on the line and having completed no additional software installs and yet the machine still panicked straight from the first boot, they engaged with the problem), they picked up my device yesterday and today I got an email letting me know that components were being replaced, including the storage module (!?!). Will update this group once it returns...
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(I should add that if your issues only happen while connected to external monitors or with peripherals attached, then they do not fall in my category 2 - my issues occurred with only the power cord attached, or with nothing attached and on battery power)
 
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1) The “resume from sleep” issue (I.e. people that just have that issue)

That's the one I have. And that on a MacPro5,1 which isn't supported anymore when running Catalina. But it has been working well on Catalina otherwise using a RX 5700 XT graphics card that I bought last November, except for the Kernel Panic on wake from sleep every now and then.

Edit:
Well, I also get the panic at times during starting up into Catalina – it just happened. :-O

The thing is, I've had problems using Windows 10 on the same computer where playing games have sometimes caused a "sudden black screen" (I'm not the only one, that problem is all over the Internet for RX 5700 XT graphics cards) and computer crash/restart. I now got a replacement graphics card since they could reproduce the problem at the store where I bought it. Everything seems stable in Windows 10 so far and this makes me wonder if the wake from sleep problem in Catalina is also gone since I used to have a faulty graphics card. At least it hasn't crashed when waking from sleep yet, but I haven't tried that many times. I'm still in 10.15.5, though. Will keep you posted...
 
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