I tried running my Grails 3.3.2 application on Java 9 and for the most part the application worked. Mail (using this plugin: org.grails.plugins:mail:2.0.0), however, doesn't work, so cannot reset password, for example.
Attempting to send mail results in this error:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mailService': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException
I believe the issue is with Spring Boot and not the plugin itself. It seems there is a problem with bean creation and Java 9 that Spring Boot addresses is their 2.x version (Grails 3.3.2 runs on Spring Boot 1.5.x).
Just wondering what the time frame is for Grails and Java 9. Thanks!
The roadmap is for forth quarter this year (2018). Grails 4 will support Spring Boot 2 (which has just been released) and is the first version of Spring Boot which will support Java 9.
https://www.grails3book.com/blog/2018/2018-03-29-grails-jdk-9.html