"macOS 10.15.4 supplemental update improves the stability & security of your Mac.

Fixes an issue where Mac computers running macOS Catalina 10.15.4 could not participate in FaceTime calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier.

Resolves an issue where you may repeatedly receive a password prompt for an Office 365 account.

Fixes an issue where MacBook Air (Retina, 13-inch, 2020) may hang in Setup Assistant or when disconnecting and reconnecting a 4K or 5K external display.

Resolves an issue where a USB-C port in your Mac may become unresponsive."

(Added a FYI on this update to the original page on macOS 10.15.4 update, with a note the Delta & Combo downloads were revised to include the supplemental update.)

• watchOS 6.2.1 includes improvements and bug fixes:
  - Fixes an issue where devices running watchOS 6.2 could not participate in FaceTime audio calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier.
  (On April 20th, Apple's security updates page notes 6.2.1 is also for Series 1 & 2.)
  
  
• iOS 13.4.1 includes bug fixes for your iPhone.
  - Fixes an issue where devices running iOS 13.4 could not participate in FaceTime calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier.
  
  - Addresses a bug with the Settings app where choosing Bluetooth from the quick actions menu on the Home screen would fail.
  
  
• iPadOS 13.4.1 includes bug fixes for your iPad.
  - Fixes an issue where devices running iPadOS 13.4 could not participate in FaceTime calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier.
  
  - Addresses an issue on iPad Pro 12.9-inch (4th generation) and iPad Pro 11-inch (2nd generation) where the flashlight may not turn on after tapping the Flashlight button in Control Center or on the Lock screen.
  
  - Addresses a bug with the Settings app where choosing Bluetooth from the quick actions menu on the Home screen would fail.

Mozilla also released Firefox ESR 68.7.0 with 5 security fixes.

Google notes Chrome 81.0.4044.92 stable channel update includes 32 security fixes.
 

• Apple and Google partner on COVID-19 contact tracing technology (press release)
  
  
• Micromat MachineProfile 1.3.14 update (use in-app update check)
  - Added MacBook Air (Retina, 13-inch, 2020) support.
  - Fixed a manufactured year issue.
  - Updated Sparkle to version 1.23.0.
  - Updated machine and location identification strings.
  - Other minor fixes and enhancements.
  
  
• 4TB (USB 3.2 Gen 1) OWC Mercury Elite Pro Review (storagereview)
  
  
• Web Animations in Safari 13.1 (webkit.org)
  
  
• OWC Joins iFixIt #FixAtHome Campaign (owc blog)
  
  
• Total War: Three Kingdoms - A World Betrayed out now for MacOS (feral interactive)
  
  
• Photoshop Alternative - Affinity Photo (sponsor blog)

• iCloud security overview
  
  
• How to clean your Apple Pro Display XDR
  
  
• Apple's Vintage and obsolete products listing updated
  
  
• How to Archive or make copies of the information you store in iCloud
  
  
• Final Cut Pro X, Motion 5, Compressor 4: Issues updating via the Mac App Store
  
  
• Final Cut Pro X, Motion 5, Compressor 4: Installation best practices
  
  
• How to select a different startup disk
  
  
• About the application firewall