Thursday, April 9, 2020

macOS 10.15.4 Supplemental Update

Joe Rossignol (tweet):

Newer devices running Apple’s recently released iOS 13.4 and macOS 10.15.4 software updates are currently unable to make FaceTime audio and video calls with older devices running iOS 9.3.5 or iOS 9.3.6, according to numerous users across the Apple Support Communities, MacRumors Forums, Reddit, and Twitter.

Juli Clover:

The macOS Catalina 10.15.4 Supplemental Update can be downloaded from the Mac App Store for free using the Update feature in the System Preferences app.

The new software introduces a fix that caused Mac computers running macOS Catalina 10.15.4 to be unable to participate in FaceTime calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier.

The combo update is available here. See also: Mr. Macintosh, Howard Oakley.

Mr. Macintosh:

I have seen some reports of the macOS Catalina 10.15.4 Update or the 10.15.4 Supplemental update bricking Macs. If your Mac has one of the following symptoms below restoring BridgeOS on your T2 Mac might help you.


Update (2020-04-10): Joe Rossignol (tweet):

A sizeable number of Mac users are experiencing occasional system crashes after updating to macOS Catalina version 10.15.4, released a few weeks ago.

The crashing issue appears to be most prominent when users attempt to make large file transfers.


Other users on macOS 10.15.4 have experienced crashes after waking their Mac from sleep, with affected systems suffering a kernel panic and rebooting to the Apple logo, according to comments shared on the Apple Support Communities, MacRumors Forums, Reddit, and Twitter.


3 and 4 finger gestures no longer work for me after the update :/ (2015 MBP). Reseting SMC/PRAM did not help unfortunately.

Update (2020-04-23): Mr. Macintosh:

I ran a few tests tonight as I was seeing some inconsistencies with some new user reports. MrMacintosh reader Neo mentioned that he saw a warning message before BridgeOS Restore. “All your media and other data will be erased from the primary disk”. Wait what??? This message did NOT show up before, when I restored BridgeOS on multiple devices. I looked back and sure enough, If you look at the 2nd screen shot under section #9 the message says nothing about losing all your user data!

Mr. Macintosh:

The Catalina 10.15.4 Update is causing kernel panics in some 16″ 2019 MacBook Pros.

Tim Standing:

A few days after the macOS 10.15 update was released, we began to hear of “Finder hangs” from DITs (Digital Imaging Technician) on movie sets. They were having their Macs stall when transferring hundreds of gigabytes of video from their 4K and 8K camera cards to their OWC ThunderBlades and ThunderBays. Anytime we hear about this type of problem, we immediately start looking for a cause.

A day later, we were able to reproduce the problem 100% of the time by copying 300 GB of large (10 GB) files from one SoftRAID RAID volume to another. Using a kernel debugger, we determined that the hang was not caused by an error in the SoftRAID driver. We then were able to reproduce the hang on an AppleRAID volume, using the AJA System Test Lite test application.

Mr. Macintosh:

Did you Install the 10.15.4 Supplemental Update on your T2 Mac, only to find that it will not power up after the Install?


This issue is similar to the 2019-001 Security Update last November that cause Data loss. The Reports are very close as it was first thought that the problem was the users fault for shutting down the Mac during the BridgeOS update.

What actually happened was, the BridgeOS Update Failed and destroyed the encryption keys.

Paul Wagenseil (Hacker News):

Supplemental Catalina update was supposed to fix problems, but just created more

Mr. Macintosh:

The 10.15.4 Supplemental Update resets the ComputerName & HostName back to default on some Macs.

Oliver Haslam:

The problem started after installing macOS 10.15.4. One fix seems to be working for most people. Some owners of the 16-inch MacBook Pro have reported that their machine restarts when asleep – often while left alone and plugged in. And the problem only started to happen once they updated to macOS 10.15.4. Thankfully, there’s a fix. In fact, it’s more of a workaround.

3 Comments RSS · Twitter

There's a really interesting thread in the MacRumors forum where people have almost reproducible kernel panics, 10.15.4 made it even worse but so far there are reports that 10.15.5 beta fixes these. I have the same issues and that's on a brand new out-of-the-box and almost empty Mac Mini with the latest version of Catalina. There really are some very big issues with the quality of Catalina.

My Mac mini 2018 was bricked after the supplemental update. No display, no LED, no fan.

Leave a Comment