Final answer:
The inability to log into vCenter Server Web Client after installing vCenter 6 is likely due to improper Single Sign-On (SSO) configuration, which includes setting up identity sources, assigning user permissions, and confirming SSO service registration.
Step-by-step explanation:
After installing vCenter 6 and not being able to log into the vCenter Server Web Client with local credentials, the issue likely lies with the configuration of Single Sign-On (SSO). To gain access to vCenter, SSO must be properly configured. A valid SSO configuration involves setting up identity sources that could authenticate users, assigning the correct user permissions, and ensuring that the SSO service is correctly registered and operational within your vSphere environment. While a valid SSL certificate and proper network connectivity are essential for the security and accessibility of the platform, SSO must be set up correctly to manage and authenticate users attempting to access vCenter. Additionally, while having the latest vCenter update may include improvements and patches, it is not directly related to the initial sign-in issue.