The URL 'http://localhost:port#/' for Web project 'xxx' is configured to use IIS as the web server but the URL is currently configured on the IIS Express web server.

C:\xxx\yyy.vbproj : error  : The URL 'http://localhost:51854/' for Web project 'xxx' is configured to use IIS as the web server but the URL is currently configured on the IIS Express web server. To open this project, you must edit the 'C:\Users\zzz\Documents\IISExpress\config\applicationhost.config' file to change the port of the site currently using the URL in IIS Express.

http://rickgaribay.net/archive/2012/11/08/the-url-x-for-web-project-y-is-configured-to.aspx

To fix the above following section must be in project file.

 <ProjectExtensions>
    <VisualStudio>
      <FlavorProperties GUID="{349c5851-65df-11da-9384-00065b846f21}">
        <WebProjectProperties>
          <UseIIS>False</UseIIS>
          <AutoAssignPort>True</AutoAssignPort>
          <DevelopmentServerPort>51854</DevelopmentServerPort>
          <DevelopmentServerVPath>/</DevelopmentServerVPath>
          <IISUrl>
          </IISUrl>
          <NTLMAuthentication>False</NTLMAuthentication>
          <UseCustomServer>False</UseCustomServer>
          <CustomServerUrl>
          </CustomServerUrl>
          <SaveServerSettingsInUserFile>False</SaveServerSettingsInUserFile>
        </WebProjectProperties>
      </FlavorProperties>
    </VisualStudio>
  </ProjectExtensions>