RE: "App inventor is unable to build this project" error, "The compiler output error was"

hello sir.. i had a problem when want building apps which says:

i hope you can help me because i had make this app for my job please

Your error messages are telling you that you have duplicate event blocks in some of your screens.

Use the red and yellow arrows in the Blocks Editor to find the errors.

Hello there,

Your project has 2+ EKSPERMEN.BackPressed events, and 2+ KEMBALI.Click events. This is not allowed in App Invenotr. Please combine the two events together, and then delete the extra event.

You are doing something like this.


Combine them together and then it will be just this.

blocks (1)

Then, delete the extra KEMBALI.Click event.

i i need delete them or just create a new?

if i just make a new name its can settle it?

I updated my post.

can i give you my project and you settle it? im not quite understand that step because im a newbie using blocks emm

Ok sure, export your project here.

Sorry, that file is too big (maximum size is 8 MB). Why not upload your large file to a cloud sharing service, then paste the link?

i cant send here..any suggestion?

You have this.


Turn them to this.


Then turn them to this by deleting the extra event.


A very good way to learn App Inventor is to read the free Inventor’s Manual here in the AI2 free online eBook - the links are at the bottom of the Web page. The book ‘teaches’ users how to program with AI2 blocks.

There is a free programming course here and the aia files for the projects in the book are here:

How to do a lot of basic things with App Inventor are described here:

Also do the tutorials at to learn the basics of App Inventor, then try something and follow the Top 5 Tips: How to learn App Inventor 2.

1 Like seriously lose it..can i send at your email please?


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