1) You have coding errors in your blocks. In the Blocks editor, look in the lower
left for the yellow and red triangle icons. If the red icon has a value larger than 0,
you have a serious coding error. Find the block in your code that has a red triangle and
fix it. Red triangles always inhibit creating an apk or running a project in the
emulator or possibly creating an aia file. Yellow triangles are more forgiving,
however, sometimes, these need to be fixed because they trip an internal warning and
you do not get a compile, so fix the yellow triangles too.
2) Your source file (the aia file) is larger than the 5Mb limit allowed in AI2 or you
put images or other resources in your Media (resources) that you do not use in the app.
All the images and sounds in resources count toward the 5Mb limit. You can program
apps larger than 5Mb in the browser, but they will not compile and might not run in the
emulator or the project may not save as an aia. If this is the case you need to reduce
the size of your image and/or sound files. Most image files can be made quite small
by resizing them using a photo manipulation program on your PC to less than 50Kb each.
3) You might have more than 10 Screens in your app. AI2 becomes unstable when more
than ten screens are used.
4) You might have set a Screen icon in the Designer Properties for your project that is too large. Use an image
sizeof 48x48 px or 96x96px instead and only use jpg or png images. *.ico files are not
supported.
5) You did not code the entire project using App Inventor 2. If you used one of the
third-party AI2 clones,you might not be able to load a Project into the AI2 compiler or
create an apk with the standard AI2.
6) If you incorrectly modified the project's Manifest files, you may have issues.
7) Sometimes, if you have LOTS of Layouts on a single screen, the apk might not
compile.
8) or the network you are using is overloaded (possibly a school network), or you have other applications running in the background, or your virus checker is doing a scan. Sometimes, just trying a few minutes later will give you a more favorable response.
9) if you have BlueStacks on your home PC. The emulator on AI2 cannot run unless BlueStacks is disabled and all of its processes are shut down.
10) Are you using Sensor controls (except for the clock)? Most Sensor controls or controls related to sms or the phone do not work in the emulators. They need to be tested on a device.
App Inventor
