If your Windows 10 has been asking you to reboot frequently with a seemingly endless update, check if the update is successful. You can do this by going to 'View your update history' settings.
If you see repeated failure for a particular update, then it could be due to bitlocker encryption.
To turn off bitlocker you can simply search for bitlocker from the search bar and turn it off
To view the progress, you can click on icon on the taskbar
Once the decryption is completed, run the Windows update again and reboot when asked to. Your update should now complete successfully. You can then go back to bitlocker and turn encryption back on.