App Inventor is unable to compile this project. The compiler error output was

[Martin M Sheriff]

App Inventor is unable to compile this project. 
The compiler error output was 
________Preparing application icon
________Creating animation xml
________Creating style xml
________Generating manifest file
________Attaching native libraries
________Attaching Android Archive (AAR) libraries
________Attaching component assets
________Invoking AAPT
AAPT time: 0.509 seconds
________Compiling source files
(compiling appinventor/ai_shacktimemonco/LifeInternationalSchool_copy/Screen1.yail to appinventor.ai_shacktimemonco.LifeInternationalSchool_copy.Screen1)

ERROR: appinventor/ai_shacktimemonco/LifeInternationalSchool_copy/Screen1.yail line 73: call to 'set-and-coerce-property!' has too few arguments (3; must be 4)

Kawa compile time: 43.923 seconds
.

[SteveJG]

There probably is  an empty socket in one of your blocks in screen1

make sure to fix your warnings before building

[Horst Schulze]

Yes, but the programm does not rally give help to found it. So you have to to this:
expand all your blocks,
clean up the bocks.
Then scroll all blocks (Arrow keys do not work! :()
And look for the empty socket.

I just did it with my projekt.

Be carefull when you move the screen and the blocks. Both is the same procedure.
Often it may happen, that you want to move the screen and by bad chance you hold an block instead of the empty space you move the block and you may have an empty socket. Mayby in future someone will fixe AI in this point so it may by possible to use arrow keys.

Horst

Horst