WCF error: "The X.509 certificate CN=localhost chain building failed ..."

Question

I'm getting this error while attempting to make my WCF client and server talk to each other.

The X.509 certificate CN=localhost chain building failed. The certificate that was used has a trust chain that cannot be verified. Replace the certificate or change the certificateValidationMode. A certificate chain processed, but terminated in a root certificate which is not trusted by the trust.

Everything works perfectly if I turn SSL certificates off.

Answer 1

I fixed the problem by turning off validation in my code like this:

client.ClientCredentials.ServiceCertificate.Authentication.CertificateValidationMode = 
System.ServiceModel.Security.X509CertificateValidationMode.None;

Where client is an instance of my service reference.

Answer 2

There is a problem with your certificate (I suppose you use self-signed cert) WCF tries to verify all the chain of issuers and expects, that finally chain would end on root trusted authority. To disable that check you could add such line to app.config branch. But this "crutch" shouldn't be used in production serviceBehaviors/behavior/serviceCredentials/clientCertificate

<authentication certificateValidationMode="PeerOrChainTrust" revocationMode="NoCheck" />