I installed Sitecore 9 for xP0 , but I'm facing an issue with xConnect I tried to Open the web https://sitecorexp1.xconnect and I see an error HTTP Error 403.16 - Forbidden Your client certificate is either not trusted or is invalid.
Windows 2012 introduced stricter certificate store validations. According to KB 2795828: Lync Server 2013 Front-End service cannot start in Windows Server 2012, the Trusted Root Certification Authorities (i.e. Root) store can only have certificates that are self-signed. If that store contains non-self-signed certificates, client certificate authentication under IIS returns with a 403.16 error code.
To solve the problem, you have to remove all non-self-signed certificates from the root store. This PowerShell command will identify non-self-signed certificates:
The reason you are getting this error is mainly because, you local machine don't have the self-signed root certificate and client certificate. You can follow the below steps to create a self-signed root certificate.