Octoprint suddenly cannot autodetect serial port on CR-10

What is the problem?

I get the error message " Error: Failed to autodetect serial port, please set it manually." despite having gotten it to work perfectly last night.

What did you already try to solve it?

Restarted printer/raspberry pi multiple times, unplugged and plugged back in printer

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)

Octoprint version .16, CR-10, using Raspberry Pi 3B,

"Changing monitoring state from "Offline" to "Detecting serial port"
Serial port list: []
Changing monitoring state from "Detecting serial port" to "Error: Failed to autodetect serial port, please set it manually."
Failed to autodetect serial port, please set it manually."