Upgrade to java-9-openjdk failed IntelliJ IDEA 2018.2.3 Ubuntu 16.04

IntelliJ IDEA 2018.2.3 Ultimate, Host OS Ubuntu 16.04 

I had been successfully running Spring boot application using openjdk 1.8. Now, I installed openjdk 1.9. when I try to set it as Project SDK under Project Structure, it shows the dialog saying :

The selected directory is not a valid home for JDK. 

I have been able to run simple java programs using the new openjdk 1.9 in terminal, so I don't think there was any problem while installing openjdk 1.9.

Please help me solve the issue.