Error Provisioning - Device provisioning failed because this device went offline
Error Provisioning
Device provisioning failed because this device went offline Please check your network connection and try again
You can see it below

However, my Internet is working fine. The only keybase isn't showing any good response. I'm using Linux Mint 19 64bit. Note log file can also not be sending
Same problem for me. Trying to provision a Windows 10 PC from an Android phone. No corporate network, no national firewall (connecting from US), no proxies. I tried both QR codes (leads to Keybase on Android phone to complain that it lost its network connectivity), and typed secret (leads to Keybase on PC to complain that it lost its network connectivity). My home network works fine, and I tried with the Android phone using WiFi and carrier network, Same result. Also tried to connect the PC using VPN. Same result.
Just happened to me also. Internet connection is fine. Something must be wrong in the app.