Compiler Error: DX returned an error code

[Taifun]

it looks like you have the error "ERROR: DX returned an error code" which occurs, if you are using several extensions, which use Proguard to obfuscate their code

which extensions are you using?
these extension developers should update their extensions, see also

Updated proguard rules

Hello everyone, If you build your extension from the App Inventor sources and use proguard, you should merge the mit-cml master branch as it includes a change that reduces the chance of classname collisions that fail the dx task when more than one extension is used. Cheers, Evan

and

Keep extension classes in extension package when proguarding (#3004)

Taifun