What has changed in macOS 10.15.6?

The Catalina 10.15.6 update released yesterday is one of the smaller updates we’ve seen for a while, at around 3 GB in size, considering that bundled in it are EFI firmware updates for all supported models.

Apple states that this update adds an option to optimise video streaming to improve battery life on compatible laptops, fixes issues where some USB mice and trackpads become disconnected, and another where the computer name can change after an update. Apple promises more detail here.

This update brings firmware updates for all recent models, for T2-equipped Macs taking their firmware to 1037.147.1.0.0 (iBridge: 17.16.16065.0.0,0). My firmware database for SilentKnight and those kept here have all been updated accordingly.

Security fixes are few in number, and include a couple for crafted audio files, with just one kernel fix. Full details are here. This update includes an update to the KEXT data file, taking it to version 15.6.1.

Bundled apps which have changed version or build numbers significantly include:

• App Store, build increment
• Mail, a major increment in build number from 3608.80.23.2.2 to 3608.120.23.2.1
• Maps, a significant increment in build number
• Music, a new version 1.0.6
• News, a new version 5.5
• Photos, a major increment in build number from 151.19.150 to 161.0.120
• Stocks, a new version 2.5
• TV, a new version 1.0.6
• Bluetooth File Exchange, a new version 7.0.6
• Boot Camp Assistant, a significant increment in build number
• Safari is updated to a new version 13.1.2, and fixes bugs using local pages as Home pages.

I’m sure we’re all hoping that the changes to Mail include fixing the bug which has been causing sporadic data loss in mailboxes, which is one of the worst outstanding issues in 10.15.5.

System Library items which have been updated significantly include:

• several Address Book plugins
• Audio Plugins HAL AirPlay driver and Bluetooth Audio Plugin driver, a significant build increment
• Finder, updated from 10.15.5 to 10.15.6 with a significant increment in build number
• Photo Library Migration Utility (CoreServices)
• Siri (CoreServices), a new version 200.5.1
• Software Update (CoreServices), an increment in build number
• Spotlight, a small increment in build number which can force rebuilding of indexes
• many AMD kernel extensions are incremented in build numbers
• many AppleIntel kernel extensions are incremented in build numbers
• AppleUSBAudio kernel extension is incremented in build number
• many Bluetooth kernel extensions are new versions
• APFS is updated from 1412.120.2 to 1412.141.1
• SMBFS is a new version 3.4.4
• WebDAV FS is a new version 3.0.1
• several important public frameworks are incremented in build numbers, and FinderSync in a new version
• QuickLook framework and plugins have been updated
• Bluetooth, Notifications, Profiles, Speech, and Startup Disk panes have all been updated
• many private frameworks have been updated.