Microsoft Technologies

The Problem
Consume web services (running on HTTPS) in SharePoint and SSL certificate is not registered in SharePoint under TRUST Authority.
Related Errors

Web Services: Could not establish trust relationship for the SSL/TLS

Server was unable to process request. ---> The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

An operation failed because the following certificate has validation errors:Subject Name: CN=xxxx.com Issuer Name: CN=XXXTRUST AuthorityName DV SSL CA - G3, OU=Domain Validated SSL, O=GeoTrust Inc., C=US Thumbprint: 3495DB5381AC3EXXXXXX9 Errors: PartialChain: A certificate chain could not be built to a trusted root authority. RevocationStatusUnknown: The revocation function was unable to check revocation for the certificate. OfflineRevocation: The revocation function was unable to check revocation because the revocation server was offline. . 1b31659d-b408-b0d3-ae61-808af97de845

Note: These errors are applicable to other web applications as well and are not limited to SharePoint.

ResolutionTo overcome this error, you need to add the certificate(of Web Service Running on SSL) to SharePoint Manage Trust Authority.

Downloading the Certificate:
First Step is to down the certificate of web service.1) Open Web service in Browser. 2) Click the Lock in address bar if you are using chrome, its on right hand side if you are using I.E
3) Click View Certificate
4) Add a new Certificate

2) Click Details

4) Select Certification Path-> Select the top level Certification Path (STEP 1)->View Certificate (SEP 2)->Details tab->Copy to File(Step 3) -> Next -> Select the format as DER encoded binary X.509 (.CER)