Serial Port Permission problem on Big Sur

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Created Jan ’21

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I have a program that has been running fine for 6 years that uploads data from a weather station (Davis Vantage Pro 2). After upgrading to Big Sur, I am getting the error message, " Serial port /dev/cu.SLAB_USBtoUART failed to open. You might need root permissions." How can I fix that.

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Answer 1

rdelmar OP

Jan ’21

I solved the first problem. It turns out Apple changed the name of the port, so the problem didn't have anything to do with permissions. The download from the device is still not working though. Each page of data is supposed to be 267 bytes, but I'm getting 64. I have an older iMac that hasn't been updated recently, and the download works fine there. This problem started on January 6th or 7th 2021. Was there some change to the serial ports around that time? Is there a way to see what was updated, and when?

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