avrdude: ser_open(): can't open device "COM17"
Have you tried using the verbose output from the IDE to see how it formats the name of the com port? There are issues with com port names when the numeric portion is greater than 9. Some sill combination of dots and slashes are needed to make windoze recognize com port names with 2 digit numbers. Bunch of morons in Redmond haven't bother fixing the problem they have caused.