Illegal reflective access by org.springframework.cglib.core.ReflectUtils$1

In JDK 9+, add the following option to the JVM to disable the warning from Spring's use of CGLIB:

--add-opens java.base/java.lang=ALL-UNNAMED

for example:

java --add-opens java.base/java.lang=ALL-UNNAMED -jar target/*.jar

No need to report it; it's a known Spring bug.

This happens because the new JDK 9 module system detected an illegal access that will be disallowed sometime in the (near) future. You can read more about the JDK 9 Module system here.

Update:

A fix for this issue is available JDK 9+ with Spring 5.1+.

This also happened to me on JDK 11 and Spring Boot 2.2.1 (Spring Core 5.2.1).

What helped was removing the dependency to org.springframework.boot:spring-boot-devtools, as suggested in some comments to Spring Framework issue #22814.

Adding to Jan Nielsen answer above, if you are using Intellij and Spring Boot 2.0.3, which depends on Spring core 5.0.7, you are still stuck and do not have the fix.

The way out for me needed two things:

• Add the --add-opens mentioned by Jan to your run/debug configuration. Just edit the configuration and look under Environment / VM Options. This takes care of silencing some of the "illegal access messages".

• I also needed to add a dependency to the jaxb-api library. I got the hint from ValentinBossi comment on this spring github issue.