When building against the latest changeset (42627d5369b3) from mozilla-central, building fennec with `mach artifact` the build completes successfully (running artifact/package/build etc) and installs on the device. However, the application crashes with the attached error log with: java.lang.NoSuchMethodError: no static or non-static method "Lorg/mozilla/gecko/GeckoEditable;.onImeRemoveComposition() The error thrown seems a bit irrelevant and probably due to something else missing higher up the chain. For reference, the last known good changeset I can build against with mach artifact is 1e700005a0dd.

In case it wasn't clear, a clean build without |mach artifact| does work though.

Yeah, this is mostly WONTFIX, but I think there's a cache updating/invalidation issue that I haven't time to track down just now, so I'll leave it open for a bit. What's happening is that you have pulled a changeset and automation hasn't produced binaries for it yet (or we're not fetching binaries once they're made available). So your local JavaScript is out of sync with the remote binaries. This is just a weakness of |mach artifact|. We could make artifact fail when an upstream commit doesn't have binaries associated with it, keeping artifact users a little behind tip.