Please contact Unity support at 'https://forum.unity.com/forums/package-manager.150/' to receive help in diagnosing your issue. Make sure to attach the diagnostic report and the accompanying log (C:\Users\rmyko\AppData\Local\Unity\Editor\upm-diag.log). Please help me. What I must do?
This means to submit a support ticket and provide them with the log files. You can make a ticket here: https://support.unity3d.com/hc/en-us/requests/new?ticket_form_id=65905