Comment 6 for bug 1648292

Please let us know what the "Selected driver" log message was. Or better yet, attach the full log output.

A similar error was encountered in bug 1355005 and although that bug is unclear it seems to generally be a case of Mir selecting a driver other than mesa-kms, and if that happens then such other drivers will reject the --vt 1 option.

So if you Raspberry Pi is selecting the mesa-kms driver then yes we have a Mir bug. If it's not and is somehow selecting the Android driver instead (and if that actually works) only then is it a bug in the snap (should not be passing --vt 1).