Ready to read, no data

Cannot connect 3D printer ANet 6. Using web interface Octo Print Version 1.3.6 with Octopi Rasberry Version 0.14.0. This is error message:

Offline: SerialException: 'device reports readiness to read but returned no data (device disconnected or multiple access on port?)' @ comm.py:_readline:2025

(there's a search function ;))