Troubleshooting Tip: How to fix error 'ERR_EMPTY_RESPONSE'

In some scenarios, after configuring a security policy on FortiWeb and testing its connection, the browser returns the following error:

 
The error 'err_empty_response' usually occurs when the backend server is hosting multiple domains and is expecting the SNI extension in the Client Hello message of the TLS handshake. In a Wireshark capture the backend server will not respond to the HTTP request, resulting in the 'Empty Response' error.

How to fix the 'ERR_EMPTY_RESPONSE' Error:

On FortiWeb, enable SNI in the backend server:

1. Go to Server Objects -> Server Pool.
2. Select the related server pool.
3. Edit the pool member.
4. Enable 'Enable Server Name Indication(SNI) Forwarding' under 'Advanced SSL settings'.
   
   

config server-policy server-pool

    edit <server-pool_name>

        config pserver-list

            edit <entry_index>

                set server-side-sni enable

            next

        end