WebSockets not supported by libcurl

[ajayjapan]

Receiving the error when I use URLSessionWebSocketTask

receive error: Error Domain=NSURLErrorDomain Code=-1002 "(null)"UserInfo={NSErrorFailingURLStringKey=wss://example.com/socket.io/?EIO=4&transport=websocket, NSLocalizedDescription=WebSockets not supported by libcurl, NSErrorFailingURLKey=wss://example.com/socket.io/?EIO=4&transport=websocket}

Any suggestions or fixes would be much appreciated.

[marcprux]

The libcurl we include in the Swift SDK for Android doesn't have websockets enabled. We'll experiment with getting it working (see swift-android-sdk/swift-docker#17), but in the short term, you might need to seek an alternative.

Starscream might work (perhaps @piercifani can confirm?), or maybe swift-nio…

[ajayjapan]

Thanks! Wasn't able to get skip-socketio to work so I tried rolling my own to no avail.

Created an issue: skiptools/skip-socketio#3

Will try to investigate other solutions.

[marcprux]

swiftlang/swift-docker#522 was just merged, so the built-in WebSocket support should work as of the next nightly-6.3 SDK release. I'll leave this issue open until we get confirmation of success.

[piercifani]

I'm sorry, I'm just reading this now!

We forked and patched Starscream so it works on Android: https://github.com/theleftbit/Starscream/tree/android

[daetojemax]

swiftlang/swift-docker#522 was just merged, so the built-in WebSocket support should work as of the next nightly-6.3 SDK release. I'll leave this issue open until we get confirmation of success.

Any updates on this? On 1.7.0 still "WebSockets not supported by libcurl"

[marcprux]

Any updates on this? On 1.7.0 still "WebSockets not supported by libcurl"

Which SDK do you have installed? E.g.:

$ skip android sdk list

swift-6.2.3-RELEASE_android
swift-6.3-DEVELOPMENT-SNAPSHOT-2026-02-13-a_android

If you have swift-6.2.3-RELEASE_android, then the older libcurl is still included (which doesn't have websockets enabled), but a 6.3 preview (which you can install with skip android sdk install --version nightly-6.3) should work.

Once Swift 6.3 is released along with the official Swift SDK for Android, it will become the default that is installed with skip android sdk install and then libcurl will work with websockets by default.

[daetojemax]

skip android sdk install --version nightly-6.3

Done, but I can’t figure out how to select between the two SDKs. How can I remove one?

[marcprux]

The latest one should be automatically used (check with skip android build --version).

You can manually remove an sdk with swift sdk remove, like so:

$ swift sdk list
swift-6.2.3-RELEASE_android
swift-6.2.3-RELEASE_static-linux-0.0.1
swift-6.3-DEVELOPMENT-SNAPSHOT-2026-01-16-a_android
swift-6.3-DEVELOPMENT-SNAPSHOT-2026-01-29-a_android
swift-6.3-DEVELOPMENT-SNAPSHOT-2026-02-13-a_android

$ swift sdk remove swift-6.3-DEVELOPMENT-SNAPSHOT-2026-01-16-a_android
Swift SDK bundle at path `~/Library/org.swift.swiftpm/swift-sdks/swift-6.3-DEVELOPMENT-SNAPSHOT-2026-01-16-a_android.artifactbundle` was successfully removed from the file system.

You can also just go into the ~/Library/org.swift.swiftpm/swift-sdks/ folder and delete it manually. If you want to delete the corresponding host toolchain, you can find it in ~/Library/Developer/Toolchains/.

[marcprux]

@daetojemax Did you get a chance to try this out? If there is any issue with the websocket support in the curl build, we'd like to get it taken care of before 6.3 ships.