Hello, friend!
For this problem, you may need to check the log. I can't give you a clear solution. I can only give you some suggestions.
1. As we know the portal service is provided by tomcat process so you can check the tomcat log.
Or you can use the following command to restart the tomcat.
sh/opt/panda/runtime/tomcat/app/tools/restart_tomcat.sh
2. Click F12 to check whether the users interface is in pending state.
If yes, log in to the active Service OM node, switch to user root, and run the following command to check whether long transactions exist:
ps -ef | grep gauss | grep "in transaction"

If yes, kill the long transaction.
kill -9 PID
Log in to Service OM again and check whether the login is successful.
Hope this helps!