"Unrecognized element 'extendedProtectionPolicy' "
I actually could have seen this listed as a 'Warning' prior to compile with the following message as well:
"The element 'transport' cannot contain child element 'extendedProtectionPolicy' because the parent element's content model is empty."
This is all in reference to the following configuration element that appeared in my client's .config file in regards to the WCF service being consumed:
Regardless of where the issue is noticed, it appears this is caused by the usage of multiple platforms. It appears that the configuration is only created when consuming the service on my Windows 7 development box, but then not recognized by other platforms such as Windows Server 2003. The 'ExtendedProtection' configuration as I understand is to help prevent attacks during the credential challange process. However due to its staged rolluot, it is not fully supported and hence the above errors are generated.
The fix? Simple for the time being. Just remove the tag and redeploy the configuration. Depending on the configuration, it may be embedded between a set of "Transport" tags. If this is the case remove the inner "extendedProtectionPolicy" tag, and shorthand the end of the transport tag "/>"