Error opening serial port 'COM6'. (Port busy)

Hi, I was just recently trying to upload a sketch to my Arduino Uno and I ran into this compile error:

Error opening serial port 'COM6'. (Port busy)

I tried unplugging it and replugging it and I then recieved this error:

Arduino: 1.6.9 (Windows 10), Board: "Arduino/Genuino Uno"

Sketch uses 1,728 bytes (5%) of program storage space. Maximum is 32,256 bytes.
Global variables use 184 bytes (8%) of dynamic memory, leaving 1,864 bytes for local variables. Maximum is 2,048 bytes.
Error opening serial port 'COM6'. (Port busy)
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xca
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xca

I have uploaded many other sketches to this same board using the same computer and IDE version, but just today I receive this problem...

Any help would be great, thanks :slight_smile:

You should check to be sure that COM6 is actually your Arduino.

This issue may be caused by other software that hijacks your serial ports by stupidly assuming that any open serial port is the device(such as bluetooth) that software is used for. Consider what other software might have been installed between the working state and the non-working state and try closing any processes that might be the culprit.