Error 400 Bad Request while registering for the first time

General
#1 
 POST http://localhost:1337/admin/register-admin 400 (Bad Request)
#2

Can you give us some more information?

#3

Screenshot (709)
Screenshot (709)826×916 67 KB

#4

Screenshot (708)
Screenshot (708)958×992 99.8 KB

#5

can you show the response payload of that request?