A web.config of project include next rows:
In the start project WCF is throwing exception and message:
"An error occurred creating the configuration section handler for system.serviceModel/behaviors: Extension element 'ELEMENT' cannot be added to this element. Verify that the extension is registered in the extension collection at system.serviceModel/extensions/behaviorExtensions."
A problem exists in file AssemblyInfo of YYY.XXX and not in config.
YYY.XXX change build number in every compilation but WCF is require a full name of assembly (AssemblyQualifiedName) and exact assembly file version number.
Open AssemblyInfo and see last 2 rows:
If a code looks like this:
You not reading current article but if acode looks like this:
This is a time to change it and resolve a problem. Enjoy.