V-16-10-97 Could not connect to the server using default credentials
If Secure Cluster mode is reconfigured, it will change the security key.
The new security key must be used to re-encrypt all the passwords that were encrypted earlier with the previous security key, else it fails to connect using the default credentials.
Hence, it will give a pop-up window requesting inputs such as username, password and the domain information as below.

To change the security key, perform the below steps:
1) Save the VCS configuration and make it writeable.
haconf -makerw
2) Run the following command:
vcsencrypt -gensecinfo -force
3) Save the VCS configuration and make it read only.
haconf -dump -makero
4) Login to the VCS Java Console should now work.