hi,please try the following methods first if you met the login problem :
1.Free up device memory by closing unnecessary apps running in the background.
2. Free up storage memory by uninstalling apps that you no longer need.
3. Make sure your game version and system version is the newest one
4.Try to re-enter or reinstall the game .
5.close and then reopen your device.
If problem still exists , please contact us with following detailed infomation--- When and How did it happen? Any hint of device? your GAME ID , device Model.
We will help as soon as possible.