My country servers are okay. I think restart will be fine. But If I lose data again. Should I download Mac OS again, If I restart?Whenever I see an Apple server error, the first thing I check is https://www.apple.com/support/systemstatus/. On another device, can you log in to https://appleid.apple.com/#!&page=signin to ensure all is well with your Apple ID?
I believe that force restarting at this stage will bring you back to the same screen. It's worth a try.
Not sure I understand what you mean about losing data. Which macOS version are you upgrading from and to? I'd try a force restart and then evaluate. If you end up back on the Apple ID log in screen and are still unable to log in, you may need to contact Apple Support.My country servers are okay. I think restart will be fine. But If I lose data again. Should I download Mac OS again, If I restart?
Yay! It might help others to know how you resolved it.Thanks everyone. I solved the problem.