SharePoint applicationHost.config file Issue

Sometimes you do not know the exact problem in SharePoint environment. You may not get any sort of error in log files. You may not open the some of sites in a farm. Sometimes, You may open the sites in one WFE server. But may not access the all the sites in another WFE server.

Cause: there are chances that your applicationHost.config might be corrupted on one of your WFE server. The file size could be 0 bytes.

Please verify the following things in all WFE servers.

Check file size in C:\Windows\system32\inetsrv\config\applicationHost.config

Go to C:\inetpub\history

Grab applicationHost.config file, replace the file into C:\Windows\system32\inetsrv\config folder.