Fuse app fails at "Assembling Android apk" — "build planning stopped due to build-tool plugin failures" (Xcode 27 / macOS 26.7)

[imjefflowe]

Brand-new Skip setup. skip create works for a Skip Lite app (builds and runs on the emulator), but a Skip Fuse app fails every time at the Android build step.

Steps: skip create → App → Skip Fuse → hello-skip / HelloSkip / no extra modules / com.gomezinc.helloskip → pre-build y, install Swift Android SDK y.

Result:
[✗] Assembling Android apk
error: build planning stopped due to build-tool plugin failures

Task :HelloSkip:buildAndroidSwiftPackageDebug FAILED

The failing command is swift build from swift-6.3.3-RELEASE.xctoolchain with --swift-sdk aarch64-unknown-linux-android28. In the log, the failure comes immediately after "Fetched .../skip/releases/download/1.9.12/skip-macos.zip from cache", with no further detail on why the plugin failed. Full log attached.

Environment:

• Skip 1.9.12 (skip checkup passes)
• macOS 26.7.1, Apple Silicon
• Xcode 27.0 (host Swift 6.4)
• Swiftly 1.1.4, Android toolchain swift-6.3.3-RELEASE
• NDK r27d
• Gradle 9.8.0, Java 27
• Android Studio 2026.1.4 Patch 1

Separately: skip android emulator create fails with "Android command-line tools version 1.0.16457483 (Android CLI) is too old (minimum: 12.0)". It looks like the newer tools report their version in a different format. I created the emulator in Android Studio instead.

Is there a known issue with Fuse on Xcode 27 / Swift 6.4, or a toolchain version I should pin?

skip-create-2026-09-30T22:00:57Z.txt

[arieltyson]

I went through your attached log, and I think it's a toolchain mismatch rather than a Skip bug. Everything on the macOS side builds with Swift 6.4 (swift-6.4.0-RELEASE.xctoolchain / Xcode 27), but the Android step runs swift build from swift-6.3.3-RELEASE.xctoolchain. SwiftPM has to compile the Skip build-tool plugin for the host before it plans the Android build. In your case, that means a 6.3.3 compiler building against Xcode 27's macOS 27 SDK, which was produced by a newer compiler. When that host compile fails, SwiftPM only reports build planning stopped due to build-tool plugin failures, which matches your log: it stops right after fetching skip-macos.zip.

Things to try, in order:

1. Confirm it: re-run the failing command from the log (.../swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift build --swift-sdk aarch64-unknown-linux-android28 ...) with -v added. The real plugin compile error should appear there.
2. Align the versions: install the Swift 6.4 toolchain and its matching Android Swift SDK (swiftly install 6.4.0, then the 6.4 Android SDK bundle), so host and Android use the same compiler.
3. Or keep 6.3.3: point it at an older SDK by installing Xcode 26 alongside and running the build with DEVELOPER_DIR=/Applications/Xcode-26.app/Contents/Developer.

The skip android emulator create "version too old" error looks like a separate issue: Skip parsing the new Android CLI version format. That's probably worth its own issue on the skip repo.

[imjefflowe]

This worked - thank you - found 6.4 and we are good to go!

…

On Thu, Oct 1, 2026 at 3:16 AM Ariel Tyson ***@***.***> wrote: I went through your attached log, and I think it's a toolchain mismatch rather than a Skip bug. Everything on the macOS side builds with Swift 6.4 ( swift-6.4.0-RELEASE.xctoolchain / Xcode 27), but the Android step runs swift build from swift-6.3.3-RELEASE.xctoolchain. SwiftPM has to compile the Skip build-tool plugin for the *host* before it plans the Android build. In your case, that means a 6.3.3 compiler building against Xcode 27's macOS 27 SDK, which was produced by a newer compiler. When that host compile fails, SwiftPM only reports build planning stopped due to build-tool plugin failures, which matches your log: it stops right after fetching skip-macos.zip. Things to try, in order: 1. *Confirm it:* re-run the failing command from the log (.../swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift build --swift-sdk aarch64-unknown-linux-android28 ...) with -v added. The real plugin compile error should appear there. 2. *Align the versions:* install the Swift 6.4 toolchain and its matching Android Swift SDK (swiftly install 6.4.0, then the 6.4 Android SDK bundle), so host and Android use the same compiler. 3. *Or keep 6.3.3:* point it at an older SDK by installing Xcode 26 alongside and running the build with DEVELOPER_DIR=/Applications/Xcode-26.app/Contents/Developer. The skip android emulator create "version too old" error looks like a separate issue: Skip parsing the new Android CLI version format. That's probably worth its own issue on the skip repo. — Reply to this email directly, view it on GitHub <#741?email_source=notifications&email_token=CQBL2SQYRCWNMY54ACRL6CD5RYHGFA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBWHE2DKMZXUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-18694537>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/CQBL2SWCTE34I6UMGAVCVKT5RYHGFAVCNFSNUABIKJSXA33TNF2G64TZHM3DANRSGIYDEMJXHNCGS43DOVZXG2LPNY5TCMBZGIZTSMRRUF3AE> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/CQBL2SUVC2LRYK7E4SBAMH35RYHGFA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBWHE2DKMZXUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVJTG633UMVZF62LPOM> and Android <https://github.com/notifications/mobile/android/CQBL2SSOBKWSQF7RMDUO7RD5RYHGFA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBWHE2DKMZXUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVZTG633UMVZF6YLOMRZG62LE>. Download it today! You are receiving this because you authored the thread.Message ID: ***@***.***>

[brillaintlcd]

You can also try listing your Swift SDKs and removing outdated SDKs to force Skip to use the latest Android SDK.

swift sdk list
swift sdk remove ...