Serial Port Not Found
Arduino Microcontroller Board
Severity: ModerateWhat Does This Error Mean?
If no serial port appears in the Arduino IDE when you plug in your board, the computer is not recognising the Arduino. This is usually a driver issue, a bad USB cable, or a faulty USB port. Try a different cable, port, or install the required driver.
Affected Models
- Arduino Uno
- Arduino Nano
- Arduino Mega 2560
- Arduino Leonardo
- Arduino Pro Mini
- Arduino clones
Common Causes
- USB cable is charge-only (no data lines)
- Missing driver for the USB-to-serial chip (CH340, CP2102, FTDI)
- Faulty USB port on the computer
- Arduino board not powered (no LED lit)
- USB hub not providing enough power
How to Fix It
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Try a different USB cable — this is the #1 cause.
Many USB cables only have power wires and no data wires. Use the cable that came with the Arduino, or a cable you know works for data transfer.
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Try a different USB port on your computer.
Plug directly into the computer, not through a USB hub. Try both USB 2.0 and USB 3.0 ports.
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Install the correct USB driver for your board.
Official Arduino Uno/Mega: uses ATmega16U2 — driver included with the Arduino IDE. Clones with CH340: download the CH340 driver. Clones with CP2102: download the CP2102 driver from Silicon Labs.
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Check if the board powers on (LED lights up) when connected.
If no LED lights up, the board may be dead, the cable may be bad, or the USB port may not be providing power. Try powering the board from a different source.
Frequently Asked Questions
How do I tell if my cable supports data?
Connect your phone to your computer with the cable. If the computer detects the phone (shows it in File Explorer), the cable supports data. If only charging occurs, the cable is charge-only.
What is the difference between CH340 and FTDI?
CH340 and FTDI are USB-to-serial converter chips. Official Arduino boards use ATmega16U2 or FTDI chips. Many clones use the cheaper CH340G. They all do the same job but need different drivers.