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I can upload a sketch but the IDE serial monitor does not open (Windows)

The Serial Monitor is an important tool in the Arduino IDE. It can be used as a debugging tool, for testing out concepts or to communicate directly with the Arduino board. If the serial monitor window cannot be opened, try these steps:

  1. Close your IDE.
  2. Open C:\Users{YourName}\AppData\Local\Arduino15\preferences.txt.
  3. Delete preferences.txt.
  4. Restart the IDE.
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