I think this issue might occur if you create a web application without creating a site collection so make sure that the web application has a site collection as the following:
- Open Central Administration > Application Management > View all site collections > Select your web application and check if it has a site collection or not !
If it does not have a site collection , try to create a site collection for this web application as the following:
Fill the data that you need and select your site template > then click on OK.
After the site collection has been created successfully try to browse the site URL , that should be now worked properly .
Note : you should be aware of When you try to create a web application and after it created successfully , you should get a dialog that informs you the
application created , and you should click on create site collection link to create a site collection as shown below.