https://developer.apple.com/documentation/macos-release-notes/macos-26_4-release-notes

macOS Tahoe 26.4 Beta 2 Release Notes

macOS Tahoe 26.4 Beta 2 Release Notes
Update your apps to use new features, and test your apps against API changes.
Overview
The macOS 26.4 SDK provides support to develop apps for Mac computers running Tahoe 26.4 beta 2. The SDK comes bundled with Xcode 26.4, available from the Mac App Store. For information on the compatibility requirements for Xcode 26.4, see Xcode 26.4 Release Notes.
AppKit
Resolved Issues
Fixed: Window resize pointer does not follow the window’s corner shape. (149726089)
Background Assets
New Features
You can now check the status of an asset pack while offline by calling localStatus(ofAssetPackWithID:) or assetPackIsAvailableLocally(withID:) on the shared asset pack manager. The former method returns all available status information. The latter returns only a Boolean value but can be called synchronously. Not all status information is available offline. (164498466)
You can make the latest version of an asset pack available locally by calling ensureLocalAvailability(of:requireLatestVersion:) on the shared asset pack manager and passing true to the shouldUpdate parameter. (166237389)
Known Issues
Setting a URL override could break apps from the App Store that use Apple-Hosted Background Assets. (169558509)
Workaround: Remove any URL override that you previously set before installing or using an app from the App Store.
Apps might crash when downloading asset packs. (169648111)
Workaround: If an app crashes due to this issue, then relaunch it. The app should then have local access to the asset pack that it was downloading when it crashed.
CoreMIDI
New Features
Audio MIDI Setup now supports Network MIDI 2.0 sessions in the redesigned MIDI Network Setup panel. You can create MIDI 2.0 connections over your local network using UDP transport for Universal MIDI Packets, enabling both Legacy MIDI and MIDI 2.0 protocol communication. Network MIDI 2.0 sessions appear alongside existing RTP MIDI sessions and support automatic device discovery through mDNS and data integrity features for reliable wireless performance. (118728162)
External Boot
Known Issues
When installing an external disk, some configurations of M1 Apple Silicon Macs might panic at boot. (170263142)
Workaround: Install to a secondary volume in APFS container instead of external disk to validate secondary boot sequences.
External Media
Known Issues
HFS external media might fail to mount automatically. (168672160)
Workaround: For macOS only, use CLI tool diskutil mount to attach the relevant disk device.
Internet Accounts
Known Issues
Exchange syncing for Calendar, Reminders and Notes might fail. (168082477)
Workaround: To continue syncing Calendar and Reminders, disable Notes syncing in Internet Accounts.
Login
Known Issues
Touch ID might not be available to unlock the screen of a standard user account after updating to this release. This occurs when FileVault is enabled and a standard user account is logged in prior to any administrator logging in following the update. (169743642)
Workaround: An administrator user should sign in to the Mac before any standard users.
macOS Recovery
Known Issues
When deleting a boot volume from the Activation Lock window in macOS Recovery, full erase functionality might not work. (170280070)
Workaround: Use the “Erase All Content and Settings” functionality from the booted OS instead of triggering from recovery.
Networking
Resolved Issues
Fixed: Multiple processes leak CFRunLoopSource objects when Automatic proxy configuration (PAC) or Auto proxy discovery are configured.
For clients of the CFNetworkExecuteProxyAutoConfigurationURL and CFNetworkExecuteProxyAutoConfigurationScript API, please check to make sure your process is not working around the leak by overreleasing the CFRunLoopSourceRef returned by those functions or the CFArrayRef and CFErrorRef passed to the completion. (166839810) (FB21376045)
Resource fork
Resolved Issues
On macOS 26.4 and later, file systems that do not natively support extended attributes restrict partial writes to the first 286 bytes of the resource fork extended attribute (com.apple.ResourceFork).
To modify the resource fork, replace the entire 286-byte range, or write beyond the 286-byte offset. (156896699)
Rosetta
Deprecations
As announced at WWDC in 2025, macOS Tahoe 26 is the last release to support Intel based Macs. Additionally, Rosetta support for apps will end after macOS 27. Starting in macOS Tahoe 26.4, users will be notified when they launch apps that use Rosetta of the upcoming incompatibility.
During the beta period, the cadence of notifications will be accelerated, enabling Apple and developers to address any issues that might occur.
There will continue to be support for older, unmaintained gaming titles leveraging Rosetta along with software running Intel binaries in Linux VMs.
Organizations using a device management service can control the notification experience with the allowRosettaUsageAwareness key. (169228455)
StoreKit
New Features
New fields revocationType and revocationPercentage have been added to Transaction. (148858551)
Resolved Issues
Fixed: Purchase Intents might not be emitted from the intents sequence when the app is launched from the background. (168958783) (FB21767675)
SwiftUI
Resolved Issues
Fixed: SwiftUI does not surface the latest .userActivity as the current user activity. (163136831)
Fixed: On macOS, a non-opaque window that hosts glass content will correctly update the backdrop content behind the glass even if the window is inactive. (166828089) (FB21375029)
Known Issues
Multiple implicit SwiftUI animations (triggered by RealityViewContent.animate or Entity.animate) that modify a RealityKit component’s properties, are combined only when the implicit animations target the same set of component properties.
For example, if you initiate an implicit animation on Transform.scale and then initiate an implicit animation on Transform.scale and Transform.translation then the animations affecting the scale property will be independent of each other, and will not combine. In this case, the most recently initiated animation will overwrite the scale property. (169723142)
Workaround: Ensure the same component properties are animated by subsequent implicit animations when possible.
Virtualization
Resolved Issues
Fixed: On certain hardware configurations, new macOS Tahoe virtual machine installations may boot to a black screen. (169654019)