Keyestudio EASY PLUG Ultimate Starter Kit Manual page 194

191
Troubleshooting:
 Upload Failed ?
This happens sometimes, the most likely case is a confused Board and serial
port, you should firstly select your proper board and port.
Or make sure you have placed all the libraries below into arduino-1.8.5
libraries folder directory.
Pay more attention that the library folder can't be overlapped.
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