![Can't open device "\\.\COM4": Access is denied error when uploading a sketch from Arduino IDE | I learned it. I share it. Can't open device "\\.\COM4": Access is denied error when uploading a sketch from Arduino IDE | I learned it. I share it.](https://gyorgybalassy.files.wordpress.com/2020/10/arduino-serial-port-in-device-manager.png)
Can't open device "\\.\COM4": Access is denied error when uploading a sketch from Arduino IDE | I learned it. I share it.
![All of a sudden BetaFlight: Failed to open serial port, when trying to repair ImpulseRC: the port 'COM7' does not exist. And I can see COM 7 in BetaFlight right now. FC All of a sudden BetaFlight: Failed to open serial port, when trying to repair ImpulseRC: the port 'COM7' does not exist. And I can see COM 7 in BetaFlight right now. FC](https://preview.redd.it/806jxpy9d7d41.jpg?width=640&crop=smart&auto=webp&s=5342174be5072fd3956e548d9ff96fd3b5a0a776)
All of a sudden BetaFlight: Failed to open serial port, when trying to repair ImpulseRC: the port 'COM7' does not exist. And I can see COM 7 in BetaFlight right now. FC
![Arduino Nano - "avrdude: ser_open():system can't open device "\\.\COM1": the system cannot find the file specified" - Stack Overflow Arduino Nano - "avrdude: ser_open():system can't open device "\\.\COM1": the system cannot find the file specified" - Stack Overflow](https://i.stack.imgur.com/PCjNG.png)
Arduino Nano - "avrdude: ser_open():system can't open device "\\.\COM1": the system cannot find the file specified" - Stack Overflow
![Problem opening Virtual COM Port on Windows 7/PuTTY - Processors forum - Processors - TI E2E support forums Problem opening Virtual COM Port on Windows 7/PuTTY - Processors forum - Processors - TI E2E support forums](https://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/355/1738.Untitled.jpg)
Problem opening Virtual COM Port on Windows 7/PuTTY - Processors forum - Processors - TI E2E support forums
Technology Dwell: When try to connect to Internet USB Modem (Huawei/ZTE/LG/Nokia), it gives error: “Unable to open serial port” or “ Unable to open COM port for USB Modem”
CCS/MSP432E401Y: Cannot open serial Port XDS110 Class Application/User UART - MSP low-power microcontroller forum - MSP low-power microcontrollers - TI E2E support forums
![Connect to a device over Serial COM Port on Windows 10 with WSL1 TTY devices with Windows Terminal and minicom - Scott Hanselman's Blog Connect to a device over Serial COM Port on Windows 10 with WSL1 TTY devices with Windows Terminal and minicom - Scott Hanselman's Blog](https://hanselmanblogcontent.azureedge.net/Windows-Live-Writer/Connecting-to-a-device-over-a-Serial-Por_115BB/image_0b37601e-8427-4349-adad-8d48d640910a.png)