I have timed the double reset as best as possible multiple times but the upload doesn't happen before the board leaves bootloader mode.

this is all I'm given as an error which doesn't appear until after the board leaves bootloader mode (after the 8 seconds) The one thing that I haven't been able to find info on is the fact that I do not have a SparkFun version, I have a non branded from ebay if that makes any difference

How can I fix?

Sketch uses 3460 bytes (12%) of program storage space. Maximum is 28672 bytes. Global variables
 use 149 bytes (5%) of dynamic memory, leaving 2411 bytes for local variables. Maximum is 2560 bytes.

avrdude: ser_open(): can't open device "\\.\COM11": The system cannot find the file specified.

Failed uploading: uploading error: exit status 1

1 Answer 1

  • Remove the power to the board
  • Hold down reset while you power it up.
  • Release reset when the IDE says that it is uploading.
  • 2
    but there will be no COM port if the 32u4 is in reset state
    – Juraj
    Commented May 3, 2023 at 11:17
  • @Juraj - It will appear once it leaves reset. The IDE keeps checking for the COM port, I believe.
    – Nick Gammon
    Commented May 4, 2023 at 6:52
  • Yeah I know about the bootloader COM port and set that up. I've been able to connect the board during reset. Just not been able to upload some dummy code with the correct processor speed before it disconnects. I'll try the holding down process tonight Commented May 5, 2023 at 15:47

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