503 service unavailable (http 503) error code is one of the most most popular http codes

What's meaning 503 service unavailable ?

503 service unavailable occurs when http server is busy and it can't handle your request

How can I fix 503 service unavailable ?

One way of solving 503 service unavailable contacting website administrator. Also periodically trying to connect website can help, because sometimes server might unable to response

Http is stateless protocol that client ask precise information to server. Then server returns response according to request content

If client send unexpected content, server returns 400 Bad request

Http status codes declared for communication between client and server by The Internet Assigned Numbers Authority

http status 400 belongs to 4xx client error – the request contains bad syntax or cannot be fulfilled