Handling the upgrading of the companion app in the old emulator is somewhat complicated. The version of companion packaged in that emulator image is quite old and it reads the upgrade bundle into memory. The challenge is that the companion is too large to fit into the heap space of the app now, so it crashes when you try to upgrade. Internally we have a tool called CompanionUpgradeHelper that we use in App Inventor to update the emulator without tripping on the memory issue, which is the process that is followed when you update via App Inventor. You may want to take the Appinventor-emulator-data file in your .appinventor folder and distribute that to people. Alternatively, you can try using the newer Windows emulator that we are beta testing, which has a newer companion. There’s a file called YaVersion.java where you can specify the acceptable versions, which you could set to the version of the companion bundled into that emulator.