iMac keeps crashing after Catalina upgrade

For me and many others responding here. If we hook up one or more external monitors to a MacBookPro running Catalina, our system crashes when left alone for a few minutes. I have a 2019 MBP which was previously a rock solid set up with Mojhave. I upgraded or removed all 32bit apps to try to have a clean system with Catalina.

In my circumstance, I have disconnected the external monitors, using the Mac as a pure laptop and the system has not crashed once in weeks.

I have hooked up a 12" iPad using Sidecar as a second monitor & it also runs perfect.

Plug my pair of Dell monitors in, crashes within minutes.

The only viable explanation is that it's the OS interacting with the graphics drivers which are causing instability with certain combinations which explains why Catalina is having problems with lots of different Mac equipment from mini's, iMacs and MBPs of varying ages, which all worked perfectly with earlier versions of macOS.

I recommend that anyone with AppleCare raises tickets which will keep the issue on Apple's radar for everyone's benefit.

Someone in this thread mentioned an attached back-up drive for Time Machine was the culprit. It was for me. I had a G-Technology connected via Thunderbolt. When I shut it off, no more constant re-booting of the Catalina OS. I then migrated my data to a new MacPro and attached that same drive. Same thing happened. I purchase a new G-Technology drive using USB-C connectors. No problem. Odd.

I just don't need access NTFS drives anymore.

I removed Paragon using AppCleaner and deleted "com.paragon-software.filesystems.ntfs" in /System/Library/Extensions (you'll need to disable SIP to do so, goto to Terminal and use "sudo csrutil disable"—don't forget to re-enable)

Restart, test

Same problem.

We purchased 2 new iMac 2019 customized i9 with Radeon Pro Vega 48 and 1Tb Samsung EVO 860 SSD running MacOS Catalina.

For sure (100% sure), problem start when you use 2 external monitors. At moment iMac sleep, can happens two issues:

a) iMac freeze (you can move mouse but no windows/program response)

b) Kernel panic and obviously restart

I made, literally, thousand of different tests, like:

· Turn off all sleeps mode

· No NTFS drives attached

· Tested with fresh Catalina installation (Using only SSD and Fusion Drive)

· Tried to use "Caffeine" APP to prevent sleeps

· Running MacOS Catalina Beta 3 (10.15.3 beta 19D62e)

No luck, always crash if I use two external screens.

Well, there are an option I don't tried yet: Install MacOS Mojave (because I use my iMac for work and I need to do id, I can not waste more time with this), so really I don't know if can be work well with 2 external screens or not.

Now, this is my provisional solution: Use only i external screen.

I'd using two monitors (3 total screens) since 4 years, so change is so important in my workflow, but always better than leave my computer to speak at phone for 5 min and come back my desk and find my mac hanged :(

My conclusions/reasons:

· This is a software problem (100% sure). I tried to compile heavy videos and raw pictures (reason I purchased this two units)

· Issue should be located at Radeon Pro Vega Driver, Sleep system or USB-C controller

· At other iMac, exactly same configuration, where we're using only one external monitor and, since we turned on first time (5 days right now), never crashed.

· My old iMac (iMac late 2013 i5 G-force 2Gb and 500Gb SSD) I was using 2 external screens (same screens I'm using right now), never crash using Catalina also (final and beta versions).

· I read from other people here, using Macbook Pro with Radeon and Radeon Pro with same problem, this is because I'm pretty sure problem is more focused on sleeping mode than radeon driver, but I can not check deeply yet (and it's not my job).

This is absolutely insane. I spent close 8000€ (like $8500) purchasing 2 amazing and powerful computers for my business, I had to negotiate with my bank, I was waiting 6 weeks since arrive (because was personalized models and, at least here, in Spain, takes a lot of time) and finally, we discover this issue.

Of course, I was talking with Apple Support. They told me "No problem sr. We'll replace your computer". Really? It means other 6 weeks waiting to receive an identical machine with same software issue? No, thanks!

Hope come soon a new Catalina. Maybe this weekend, if I have more free time I decide to install Mojave and try. I promise come back here and share with you my new test.

Downgrading completely resolved issues I had...i.e. I completely wiped out the existing partition then pulled down High Sierra from Apple and installed, then restored data from data partition Catalina creates. Then destroyed Catalina data partition to free up disk space.

Steve

After 2 days of 10 hour continous photoshop work on set

I can confirm now that downgrading the new 27 inch 2019 Retina iMac

3.6GH intel core i9

128 mb of OWC RAM

Radeon Pro Vega 48 8GB

from Catalina to Mojave solved the frequent crashes !

Hello,

iMac 2019 i9 with 40gigas, external HDs and monitor. Upgrade from Mojave to Catalina 10.15.3. Results : Kernel Panic 10 times a day. Boring.

What I did to resolve this problem:

• Etrecheck to detect and delete unnecessary files,
• Go64 to remove ALL 32-bit processes and applications,
• Remove Adobe CC (lots of 32bits things),
• Onyx to clear caches,
• Restart,
• Reinstall Adobe CC (seems that Adobe remove all 32bits things with Calatina installer),
• In the energy saver settings : Turn display off after : Never“,
• In the energy saver settings : Disable the option “Put hard disks to sleep when possible“.

For now, no KP and crashes.

I tried to activate the function to turn off the screen but this would cause a crash.

Hope this helps.

my iMac (2012) was crashing every 15 mins and i have externals and the only time it started to do this was after i upgraded to Catalina. I tried pretty much all of the things suggested on various posts but nothing help, including trying out the beta. I finally downgraded to Mojave and am happy to report that my iMac hasnt crashed for the last 24 hours. I followed the instructions on macworld.uk site on how to download the OS mojave and how to create bootable installable on a usb flash drive and was successfully able to complete the downgrade. All it cost me was the price of a flash drive. hope this helps others too. i will sit on mojave and not upgrade till Apple fixes Catalina.

I've been suffering under the same problem as everyone (and have posted previously here) for some time. 2019 27-inch iMac w/3.8 Ghz 8-core Intel Core i9 connected to 2 external monitors and a Thunderbolt SSD drive. I upgraded to the latest Catalina 10.15.4 "Supplemental Update" (19E287) and it seems to have resolved the problem (for me anyway). Haven't had a panic crash for days. (Fingers crossed)

Restore from the Time Machine backup that you were advised to make before upgrading.

Or use Recovery and install the OS it came with.

https://support.apple.com/en-us/HT204904

A truly brand new Mac from Apple will come with Catalina pre-installed

I might have found the culprit. I have a 2019 i9 with stock memory, 2 Dell 4K monitors on either side and since Catalina beta. Crash crash and more crashes. You know the same Watchdog issue.

Drive was full and I deleted the Photos Library.photoslibrary - low and behold...no crashes for 2 weeks. No background sync processes for Photos are running. As soon as I created a new library.....the crashes began again. As soon as I deleted the Photos Library.photoslibrary - no more crashes.

I've been working on a solution for 6 months...but this is the closest to being able to reproduce this consistently as I have gotten.

https://discussions.apple.com/thread/251140242?page=1

Same deal. 2019 MBP with Vega20 and 2x LG 4K monitors.

I haven't seen the issue with 1 external screen attached. Only with 2.

Restored my last Time Machine backup before I upgraded to Catalina 👍🏼

EDIT: While I've definitely seen the log you've shared, I've actually seen 2-3 different panics. Reported all of them and sent them in to Apple Support.

POSSIBLE SHORT-TERM SOLUTION:

I have turned off automatic graphics switching while I am plugged in to my two external thunderbolt 3 4K monitors. I have not a had a crash for nearly an hour, where I was getting a crash usually within ten to fifteen minutes of startup.

it seems it doesn't crash anymore after I empty the Pictures folder. Now, I'm going to restore photos library one by one carefully in order to not let that photoanalysisd go crazy.

Whoever has a similar problem, you might wanna empty Pictures folder first after backing up your photos to Time Machine.