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Apple released the second developer beta of watchOS 10.5 on April 16, 2024. Its build number was 21T5555d. Apple did not publicly identify a major new feature in the beta or publish a detailed beta-2 changelog, so its main value was giving developers a chance to check app compatibility ahead of the public update.
This is a historical release: watchOS 10.5 later shipped to everyone as build 21T576 on May 14, 2024.
What was in watchOS 10.5 beta 2?
Beta 2 followed the first watchOS 10.5 beta, build 21T5545f. Apple issued the update through its developer beta channel alongside second betas for other operating systems, including iOS 17.5, iPadOS 17.5, macOS 14.5, tvOS 17.5 and visionOS 1.2. Contemporary reporting places the release on April 16, 2024, and identifies the watchOS build as 21T5555d (iClarified; MacRumors forum release thread).
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No major user-facing change was publicly documented for beta 2. That does not prove the update contained no changes: beta releases can include fixes or under-the-hood work that Apple does not itemize. The available evidence supports describing this one as a developer testing release, not as a feature update with a confirmed headline addition.
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![Apple Watch Series 11 [GPS 46mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - M/L. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/416RQ0rtsUL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
What Apple’s watchOS 10.5 notes documented
Apple’s watchOS 10.5 release notes say the 10.5 SDK supports development for Apple Watch devices running watchOS 10.5 and is bundled with Xcode 15.4. They also list two resolved StoreKit issues:
- Tapping the Terms of Service button in
SubscriptionStoreViewcould cause a crash. ExternalPurchaseLink.open()might fail to open an external purchase URL.
Those are fixes documented for watchOS 10.5 and its SDK. Apple’s notes do not establish that either fix was introduced specifically in beta 2, so they should not be treated as a beta-2 changelog.
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![Apple Watch Series 11 [GPS 42mm] Smartwatch with Rose Gold Aluminum Case with Light Blush Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31caPPnRysL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Who was the beta for?
It was intended for developers using Apple’s developer beta distribution system to test apps and compatibility. A developer beta is distinct from a public beta, and the release should not be read as a general recommendation for everyday watch owners. Apple describes beta software as pre-release software for testing; consult its beta installation guidance for the relevant account and device requirements.
Whether a watch could receive the update depended on watchOS 10 compatibility as well as the paired iPhone’s software and setup. The available information here does not support a complete model-by-model compatibility list, so check Apple’s compatibility information for the specific watch and iPhone rather than assuming every watch that can run watchOS 10 would be offered the beta.
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![Apple Watch SE 3 [GPS 40mm] Smartwatch with Starlight Aluminum Case with Starlight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31YiTby0pOL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
How developers installed it at the time
For the watchOS 10.5 beta era, the documented flow used beta-update controls on both the paired iPhone and Apple Watch app. Menu wording can change between operating-system versions; these steps describe the general route rather than asserting that every label is unchanged today:
- On the iPhone, open Settings > General > Software Update > Beta Updates and select Developer Beta.
- Open the Apple Watch app on the iPhone, then go to My Watch > General > Software Update > Beta Updates and select the developer beta option.
- Start the update when it appears, and enter a passcode if prompted. Keep the watch on its charger and near the iPhone while the update downloads and installs.
Apple’s beta guidance lists practical prerequisites including a watch battery of at least 50%, the iPhone connected to Wi-Fi, the devices kept near one another, and the iPhone running the required beta software. Developer Mode may be needed for locally installed apps and build-and-run testing. A beta selection does not guarantee an update offer: eligibility, hardware compatibility, pairing, and the required iPhone version all matter.
Rank #4
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Midnight Aluminum Case with Midnight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31Gq8SToFJL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
What to test on a dedicated watch
For a developer, the useful question is not only whether the update installs, but whether the app still behaves correctly on real hardware. Check app installation, launch and upgrade paths; complications and widgets; background refresh and scheduled work; notifications and handoff between iPhone and watch; and health, workout, motion, location and connectivity workflows. These are sensible compatibility checks, not a claim that beta 2 changed each subsystem.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchApps using StoreKit deserve particular attention. Test subscription screens built with SubscriptionStoreView and any flow that calls ExternalPurchaseLink.open(), especially where those interactions matter to purchases or customer support. Also watch for crashes, battery drain, slow performance, unreliable pairing, or behavior that differs across supported watch models.
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![Apple Watch Series 11 [GPS 42mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/41s72HIk5TL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Risks and recovery considerations
Beta software can be less reliable than a public release. Avoid putting it on your primary watch if you depend on it for reliable health, workout, notification, payment or emergency-related functions. Use a dedicated test device where possible and confirm that your data is backed up before installing. Apple says Apple Watch data is backed up to its paired iPhone.
Do not assume you can remove a watchOS beta using a normal downgrade option in Settings. A failed update or recovery problem can require Apple service; Apple’s beta support documentation warns that some Apple Watch recovery situations need to be handled by Apple. If an update does not appear, check beta eligibility and selection, the paired iPhone’s software, battery level, Wi-Fi and device proximity before taking more drastic steps. Avoid unofficial firmware downloads or erasing the watch simply because an over-the-air update is delayed.
What happened after beta 2?
Apple continued the 10.5 beta cycle after this release. Later milestones included beta 3 (21T5560d), beta 4 (21T5571a), and a release candidate (21T575). The public version shipped as build 21T576 on May 14, 2024 (build sequence; release-candidate report; public-release report).
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