"App Inventor is unable to compile this project" Unspecified error. No warnings

I can't build my project, both with QR and "save on your computer" gives me the error that you see in the attached.

If I try Ai Companion it works perfectly.

I have already tried several computers but nothing.

I had build the apk two days ago with no problems, then I do several changes to the project in Designer and in Blocks but MIT doesn't report any warning, and everything works fine on Companion.

Where can I find the problem? Thank's

--

Hi Marco,

I downloaded the sources for your AIA file and I see that there is an external_comp folder there with a number of (irrelevant) Java classes. Did you previously upload an extension, or otherwise modify the project outside of App Inventor? This is an abnormal structure and the compiler is confused about how to deal with it.

Evan

--

Hi Evan, thank you for answer, yes i had try to install an extension but with no success. When i had insert the url of extension nothing appears on screen.

this is the problem!?
can i solve it?
thank you

--

When i had insert the url of extension nothing appears on screen. 

any example of an url you are using?

usually you import an aix file from your computer into your project

Taifun

--

Here is a version with the errant files removed. Try this.

Evan

attached file: Questionario_117161728171255986894.aia

--

Thank you Evan!!!!  It's work perfectly!!

I will never use extension! :)

Thank's Taifun for answer, i don't remember the url of extension, i was searching an extension to send attachment in mail but i solve with Share Social.

Thank you!!

--