In an HTTP request and response, the client and server can place additional information in HTTP headers. Since the “411 Length Required” status code is a client-side error, this means that there was a problem with the request header.
You can use the request header to provide context about the request, allowing the server to tailor its response. The request header can include:
Source IP address and port number
Content-type
Browser type (user-agent)
Requested URL
HTTP headers can also define the size of the entity-body. By specifying the content-length value, you can let the server know the anticipated size of the request. This is identified in a decimal number of octets.For example, you can view the content length of a web page by right-clicking on an element and selecting Inspect. Under Network, you should find information about the request header.