If you are working with Sitecore Rocks and trying to connect Sitecore Rocks with your Sitecore project in Visual Studio then there are some chances to spot No Service Error shown in below screen-shot.
Well, there is simple solution. Go to your Sitecore Webroot folder and open Web.config file
Remove <deny> tag from Web.config file for <location path=”sitecore/shell”> tag only.
That’s it! Now try to connect again with Sitecore Rocks and you should have connection success.
In case, you are still getting connection error, then it is advised to close Visual Studio project and open again and try. Hope this may help someone!