The Arduino error avrdude: stk500_getsync(): not in sync means the computer and board failed to synchronize during sketch upload. It does not, by itself, prove the board is dead or identify one cause. Start with the selected board and port, then check the USB cable, connections, and serial-port use before trying board-specific recovery steps.
What the error means
stk500_getsync() is an upload communication failure. A wrong board selection, the wrong port, a cable that cannot transfer data, something connected to the serial pins, or another application using the port can all prevent a successful upload. Arduino’s error troubleshooting guide recommends checking configuration and connections before moving to board-specific diagnostics.
Work through the basic checks first
1. Select the board and its current port
- In Arduino IDE, choose the exact board model in the board selector.
- Choose the port currently associated with that board. If you are unsure which one it is, disconnect the board, note the available ports, reconnect it, and refresh the board selector or the Tools > Port list. Select the port that appeared.
- Try the upload again.
A port that is missing or inaccessible may produce a different message, such as a ser_open() error. That is distinct from a stk500_getsync() synchronization failure, although checking the selected port is still a sensible first step.
2. Check the USB cable and physical connection
- Make sure the board powers on, then try a USB cable known to transfer data. Arduino’s guidance is explicit: “Make sure you are using a data transfer USB cable (charge-only cables will not work).”
- If possible, try another cable and a different USB port on the computer. Connect directly rather than through a hub while troubleshooting.
- Match the cable connector to your specific board; Arduino boards do not all use the same USB connector.
A different cable is a useful test only if the current one may be charge-only or faulty; it is not a guaranteed fix.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
3. Disconnect devices from RX and TX
Remove jumper wires, shields, or other devices from digital pins 0/RX and 1/TX while uploading. Those pins carry serial communication on many classic AVR boards, so attached hardware can interfere with the upload. Disconnect other unnecessary devices too, then try again.
4. Make sure another application is not using the port
Close other Arduino IDE instances, Serial Monitor windows, and any other application that may have the board’s serial port open. If the port still appears busy, restart the computer and retry. On Linux, check Arduino’s guidance for serial-port access and permissions.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Apply checks for your board
Classic Arduino Nano: try another processor selection
For a classic Nano, open Tools > Processor and try a different available processor option. The appropriate selection depends on the particular board and its bootloader; Arduino’s general error guidance does not specify one choice that is correct for every Nano. If you are using a third-party board, its USB interface hardware or driver may also be relevant. Arduino separately calls out some third-party boards that use WCH CH340 chips.
Native-USB boards: use bootloader mode only if applicable
Some boards with native USB can enter bootloader mode when you press RESET twice quickly. After doing so, check the port list again: the bootloader may appear on a different port. This procedure is not interchangeable across Arduino architectures. Arduino says the UNO R3, Mega, and classic Nano use dedicated USB-to-serial chips and do not use this native-USB bootloader mode. Follow the instructions for your exact board in Arduino’s upload troubleshooting guide.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
When to try loopback or bootloader recovery
Use a loopback test only if your board is one of the supported classic AVR models Arduino lists: classic UNO, UNO Rev3 variants, classic Mega variants, or classic Nano. The test helps check whether the serial chip is working; it is not a universal test for every Arduino board. Follow Arduino’s board-specific loopback instructions rather than applying the wiring steps to a different model.
If the loopback test passes, or your board does not support that test, Arduino notes that reprogramming the bootloader may resolve persistent upload problems. Treat this as a later diagnostic step, not the first fix: it requires instructions and, depending on the board, a suitable programmer. Use guidance for your exact board and programmer before proceeding.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
If uploads still fail
Repair the board package installation
If the board is detected but uploads continue to fail, corrupted board-package files are another possibility. Arduino’s general upload guidance suggests deleting the Arduino15 folder, restarting the IDE, and reinstalling the relevant board package. Because this removes installed package files, use Arduino’s instructions for your operating system and reinstall the package before trying to upload again.
Gather details for troubleshooting help
When asking for help, include the exact board name, operating system, Arduino IDE version, and the full verbose upload output. Also describe which port is selected and what checks you have tried. Those details help distinguish a board-selection or connection problem from a board-specific recovery issue.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsQuick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
