Solution 1:

Click on the Home Page Flyout menu :

Applications > AR System Administration Console > System > General > Centralized Configuration

Select Component Type: com.bmc.arsys.server.shared > *

The Redirect-URL parameter will typically have following values 

cmdb.<ARServer>:http://<ARServer>:<Jetty Port>/cmdb/index.html;
cmdb.<ARServer> : This value will use the AR Server from your Remedy ITSM URL as Follow https://<MidTier Server>.<Domain>:<Port>/arsys/forms/<ARServer>

If there are 2 servers in the server group, ARServer1, and ARServer2, with an AR Load Balancer in front the Redirect-URL parameter will need to change as follows

cmdb.<AR_LBName>:http://<AR_LBName>:<Jetty PORT>/cmdb/index.html;cmdb.<ARServer1>:http://<AR_LBName>:<Jetty PORT>/cmdb/index.html;cmdb.<ARServer2>:http://<AR_LBName>:<Jetty PORT>/cmdb/index.html;

If you continue with the error, then you can try using a specific AR Server name to bypass the LB as below:

cmdb.<AR_LBName>:http://<ARServer1>:<Jetty PORT>/cmdb/index.html;


Please refer to below blog to know more about the new CMDB UI or CMDB Portal:
https://communities.bmc.com/community/bmcdn/bmc_it_service_support/cmdb/blog/2018/04/03/everything-that-you-need-to-know-about-accessing-new-cmdb-ui