Serial Monitor or Sketch is Invisible

The IDE saves the screen position of the monitor window and sketch window in the preferences.txt file with lines like

last.serial.location=567,23,842,748
last.sketch.default.location=2000,448,500,600

If you do something weird with your screen resolution they may be positioned off the viewable screen. To fix it: Open the preferences.txt file by clicking on it in the preferences menu, then quit the Arduino IDE, then delete the location lines and save preferences.txt, then restart the IDE.

Cannot Compile for M0 (Windows)

Many people have found ways to corrupt their windows installation so it won’t compile. This compile failure can result from several things:

Trying to compile with zipped files. Windows will let you browse the contents of .zip files while they are still compressed, but Arduino will fail to compile if there are any compressed files in the tree. After you extract files from a zip archive, delete the archive.

Multiple installations pointing to different sketchbook folders. Make sure there is only one installation of the program on your computer.

If you can’t get your code to compile on windows, delete all installations and create a portable installation following this page of instructions https://www.arduino.cc/en/Guide/PortableIDE

Itsy Bitsy Board Won’t Talk to USB

Make sure you have the right board and port selected under tools.

Your first try should be to double click the reset button on the Itsy Bitsy so the large LED turns green and the board is ready to receive a download.

If that doesn’t work, try unplugging and replugging the USB, or going to a full power down and reboot.

Test with somebody else’s board to be sure the problem is your board. If it works with a different board, try reinstalling the bootloader https://learn.adafruit.com/introducing-itsy-bitsy-m0/uf2-bootloader-details on your board.

In most cases, walking through from a power-on restart can reliably upload code, and you should make notes of any particular steps required for your computer/OS combination. For example, some machines seem to disconnect the board on every compile and reconnect it on a different windows COM port. To track what is going on, open a windows explorer window, visible beside your code window. Double click reset on your Itsy Bitsy and the dotstar should go green and a new drive called ITSYBOOT should appear in your list in addition to your C: drive. Compile and upload your code and that drive should disappear. Open the Serial monitor so you can see all three windows on your screen (reconnect Tools/Port if needed). Leave all three windows open during your next compile.

This page https://learn.adafruit.com/introducing-itsy-bitsy-m0/troubleshooting is mostly about circuit python issues, however it has some useful suggestions about making sure the Windows communications configuration is working. https://learn.adafruit.com/introducing-itsy-bitsy-m0/troubleshooting#device-errors-or-problems-on-windows-3094694-15 might be especially helpful, as I notice most problems seem to be with COM6 and COM7, so other devices might be blocking things up.

If you still can’t get your code to load on windows, delete all installations and create a portable installation following this page of instructions https://www.arduino.cc/en/Guide/PortableIDE