USB input/output error

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Read this if you get "Input/output" errors when trying to use a USB device with a CDC-ACM class interface (RS-232 serial link emulation). These devices include USB-to-RS232 adapters, USB modems, mobile phone tethers, and USB devices that use Heyes modem "AT" style commands.

The `minicom` command gives this error:

minicom: cannot open /dev/ttyACM0: Input/output error

The `screen` command gives this error:

Cannot open line '/dev/ttyACM0' for R/W: Input/output error
Sorry, could not find a PTY
[screen is terminating]

The `kmobiletools` command will simply fail to connect to your mobile phone without a distinct error.

The problem is with your USB hub or host adapter.

Unplug the device and plug it into a different hub or USB port on your system. That will usually fix the problem. If you only have a few ports and no hub then it means your host adapter is confused. The only solution I have found is to reboot.