shows Page not found on the Title tab

Hi all,

After upgrading Appian version 19.3 from Appain version 18.4. While testing our website url which is Generated using Web API,

while running our website url in any browser we are getting Page not found title showing on the browser tab (Title Bar). For earlier Appian version 18.4 it  was working fine.

Has anyone faced the mentioned issue. Can you please help in this regard.