Apple released iOS 27 developer beta 4 on July 20, 2026. The official build number is 24A5390f, and it’s landing two weeks after beta 3.
This isn’t the beta where Apple drops another giant pile of headline features. Beta 4 is the tightening-the-bolts release. Siri gets more polish, Photos and AirPods pick up useful controls, ProRes Log 2 appears for supported cameras, and Apple’s current release notes contain a long list of fixes across CarPlay, Safari, Shortcuts, alarms, system stability, and more.
There’s also a curious dual-battery reference buried in the code, but we’ll get to that. It’s a clue, not a feature.
If your Apple ID is enrolled for developer betas, you can check for the update under Settings > General > Software Update > Beta Updates. As always, this is prerelease software. Don’t put it on the iPhone you depend on unless you’re comfortable dealing with broken apps, battery weirdness, and the occasional software gremlin.
Apple confirmed the release and build number on its developer releases page.
What’s Actually New in iOS 27 Beta 4?
The most visible changes in beta 4 center on Siri, Photos, media controls, and a handful of Liquid Glass refinements.
Most of these discoveries come from early hands-on testing, while Apple’s developer notes focus more heavily on resolved issues and API changes.
Siri Gets a New Welcome Screen and More Voice Controls
The first time you launch Siri AI in beta 4, you may see a new “An All-New Siri” welcome screen. It’s a small presentation change, but it shows Apple’s still refining how users are introduced to the rebuilt assistant.
The Siri voice interface has expanded too. Early testers found additional English voice regions, including Australian, British, Indian, Irish, and South African options. Two enhanced voices currently support adjustable Pace and Expressivity, while several others are still labeled as coming soon.
Apple’s also added a Preview setting for the Siri app. You can choose how many lines of each conversation appear in the list, from one to five, or hide previews entirely.
None of this reinvents Siri. It does make the experience feel less like a WWDC demo that escaped containment and more like something Apple expects normal people to use every day.
Photos Adds “Zoom Photos to Fill”
There’s a new Zoom Photos to Fill option in Photos settings, and it’s enabled by default.
When a photo’s aspect ratio is close to the iPhone display, Photos can slightly zoom the image so it fills more of the screen. Some people will prefer the cleaner edge-to-edge presentation. Others will immediately turn it off because cropping even a sliver of a photo feels like a personal attack.
The important part is that Apple gives you the choice.
ProRes Log 2 Arrives for Supported iPhones
If you’ve got Apple ProRes enabled under Settings > Camera > Formats, you can now choose between Log and Log 2 video encoding.
Log 2 preserves more image information for color grading and post-production adjustments. Most iPhone owners won’t touch it, but it’s a meaningful addition for creators using the iPhone as a serious production camera.
Apple’s spent years turning the Pro iPhone camera into a legitimate filmmaking tool. Log 2 is another brick in that wall.
AirPods Controls Get a Liquid Glass Refresh
AirPods controls in Control Center now use a smoother sliding interface. Press and hold the control, and you can move between listening options with a more fluid Liquid Glass animation.
Beta 4 also surfaces the newer adaptive listening control for compatible AirPods Pro models. It’s less menu hunting, and the control feels more consistent with the rest of iOS 27.
Apple TV Can Automatically Download the Next Episodes
The Apple TV app now includes a smarter automatic download option. Turn it on, and it can download upcoming episodes from a series you’re watching, then remove completed episodes afterward to save storage.
It’s the kind of feature Apple rarely gives ten minutes of keynote time, but it may be more useful than half the features that do get stage time.
Apple Reverses a Few Beta 3 Visual Changes
Beta 3 introduced a noticeable depth effect when pulling down Notification Center. That’s gone in beta 4.
The white Lock Screen control buttons are back in both light and dark modes, and the blur effect has returned to the Home Screen’s Today View. The Liquid Glass volume slider also looks slightly more transparent.
That’s beta season in a nutshell. Apple tries something, the internet argues about it for two weeks, and the next build quietly moves the furniture again.
The Bigger Story Is the Fix List
Apple’s current iOS and iPadOS 27 beta 4 release notes are packed with resolved issues. Not every item is a flashy beta 4 feature, but together they show where Apple’s spending its time as the fall release gets closer.
Some of the most relevant fixes include:
- AirPlay: Home Theater connections should no longer fail when a PIN or password is required.
- Battery and booting: Apple fixed an issue where a deeply discharged device could remain stuck on the red dead-battery screen.
- Camera: Portrait mode blur could render incorrectly in some photos.
- CarPlay: Steering-wheel next and previous track buttons could fail, and stereo music could become silent after Spatial Audio playback.
- Clock: Some users couldn’t stop a ringing alarm from the Lock Screen without unlocking the phone.
- Files: Deleting items from Recently Deleted could fail or take an unusually long time.
- Mail: Messages could display content that didn’t match the subject line.
- Safari: The tab bar could disappear, and some Safari Intelligence features could appear before their assets finished downloading.
- Screen Time: Restrictions could fail to apply to child accounts.
- Shortcuts: Migrated Focus automations, Writing Tools actions, and some on-device Use Model actions had problems.
- Siri: Apple lists fixes for voice-response failures, incorrect contact matching, failed email composition, and CarPlay navigation requests.
- System stability: Devices could freeze or panic while idle.
That last one matters. A new Siri voice is fun. A phone that doesn’t randomly freeze while sitting on the table is better.
Some Bugs Are Still Very Much Alive
Beta 4 still has known issues, because the word “beta” is doing real labor here.
Apple says Siri may still respond slowly in CarPlay when the device is hot or the network is poor. Siri can also struggle with selected photos, cut off words during navigation, or return incomplete Maps information.
The status bar may appear blurred while apps are open. Writing Tools can become unresponsive when interacting with the plus button. Weather Highlights is still limited to US English. Some Shortcuts configurations can still fail when edited through natural-language tools.
So yes, beta 4 is more stable than the first builds. It’s still not the finished iOS 27 experience.
Does Beta 4 Hint at a Foldable iPhone?
Early code inspection reportedly uncovered a system message referring to an iPhone with multiple batteries. That’s already fueled speculation about Apple’s long-rumored foldable iPhone, since a folding design could use separate battery cells across each half of the device.
It’s an interesting clue. It isn’t confirmation.
Internal code can reference prototypes, abandoned hardware, test configurations, or products that never ship. Treat the dual-battery string as evidence that Apple’s experimenting, not proof that a foldable iPhone is around the corner.
Should You Install iOS 27 Beta 4?
If you’re already running the iOS 27 developer beta, beta 4 is probably worth installing. The stability fixes alone make it the better place to continue testing.
If you’re on the public beta, wait for Apple to release the corresponding public build instead of switching channels just to get it early.
If your iPhone is essential for work, banking, authentication, health devices, or anything else you can’t afford to have break, stay on the stable release. Beta software is a preview, not a personality test.
The Bottom Line
Beta 4 isn’t the loudest iOS 27 release, but it may be one of the more important ones so far.
Apple’s polishing Siri, improving creator tools, cleaning up Liquid Glass, and fixing the ordinary problems that determine whether an operating system feels finished. The visible additions are useful. The long list of stability and reliability fixes is the real headline.
We covered the deeper developer changes in iOS 27 beta 3, including Neural Engine restrictions, the new on-device Dictation model, stricter TLS requirements, and major SDK changes.
iOS 27 is still scheduled for a broad release this fall. Beta 4 suggests Apple’s moved from building the skeleton to sanding down the sharp edges.
