Did you place cglib in a module? This is supposed to solve your problem. Alternatively, you can change the setting that forbids accessing internal API.

cglib is a transitive dependency so I can't put it in a module. As I mentioned above, --add-opens=java.base/java.lang=ALL-UNNAMED doesn't appear to work. Minimal reproducible example using Java 16:

import net.sf.cglib.proxy.Enhancer;

public class Main {
    public static void main(String[] args) {
        new Enhancer();
    }
}

@raphw can you please explain what you mean by you can change the setting that forbids accessing internal API.? thank you

@wind57 This has been discussed here and an alternate approach for users (unless cglib plans to upgrade) is suggested. i.e to make use of the override --illegal-access=permit.

I believe the correct fix for this problem would be for cglib to ship with a module-info.java that imports java.base. You can use multi-release JARs to maintain support for older JDKs. Search for multiReleaseOutput at https://www.baeldung.com/maven-multi-release-jars

JEP 403 targeted for JDK 17 (release planned for Sept 2021) will remove --illegal-access flag. That will be equivalent to --illegal-access=deny.

cglib can go with standard replacements for the most commonly used internal elements of the JDK.
In this case instead of protected java.lang.ClassLoader::defineClass method use java.lang.invoke.MethodHandles.Lookup::defineClass (since JDK9).

Same issue here, using --illegal-access=permit is not an option for my users, especially with Java 17 coming up.

FYI: I've just implemented an initial hacky workaround to make cglib some kind of work with JDK17. See this commit rototor@cc8632e

It's ugly because it needs to get a class in the package of the class going to be defined. To do so it does some "magic" with the class path, including (in my case) stripping "Wicket_Proxy_" prefixes.

Feel free to use this as a base to make a clean version of it. (The real solution for me would be if Wicket just migrated to ByteBuddy...)

Is there likely to be a Java 17 compatibility fix in the near future? I know Apache Wicket are affected by this and looking at putting in a fix but if a fix is planned at this end, they don't need to worry. https://issues.apache.org/jira/browse/WICKET-6913

Instead of layering one hack on top of another, wouldn't it be better to implement this using public methods that are guaranteed to continue working in the future?

Any update for the fix for java 17?

Last commit to this project is August 2019. Methinks it's time to bury it.

@adityajoshee I don't think that there will be a fixed release for JDK 17. If at any way possible you should migrate to ByteBuddy. If you have CGLib as dependency of some other library you use, you should try to migrate to the latest version of this library. E.g. Wicket and Hibernate already migrated away to ByteBuddy.

As a last resort you can use my commit rototor@cc8632e as a base for your own local built and deployed cglib version.

FYI all, I added a note to the top-level README about its current state:

IMPORTANT NOTE: cglib is unmaintained and does not work well (or possibly at all?) in newer JDKs, particularly JDK17+. If you need to support newer JDKs, we will accept well-tested well-thought-out patches... but you'll probably have better luck migrating to something like ByteBuddy.

For those unable to migrate to ByteBuddy easily, Spring Framework maintains patches for cglib that include compatibility for Java 17, you could do a similar thing and embed cglib into your sources:

https://github.com/spring-projects/spring-framework/tree/main/spring-core/src/main/java/org/springframework/cglib

try add jvm option
- JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

For those unable to migrate to ByteBuddy easily, Spring Framework maintains patches for cglib that include compatibility for Java 17, you could do a similar thing and embed cglib into your sources:

https://github.com/spring-projects/spring-framework/tree/main/spring-core/src/main/java/org/springframework/cglib

I have replace cglib to the one embeded in spring framework, but the issue still occurs:

org.springframework.cglib.core.CodeGenerationException: java.lang.reflect.InaccessibleObjectException-->Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @385e9564
at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:598) ~[spring-core-5.3.23.jar:5.3.23]
at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363) ~[spring-core-5.3.23.jar:5.3.23]
at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110) ~[spring-core-5.3.23.jar:5.3.23]
at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108) ~[spring-core-5.3.23.jar:5.3.23]

It can be solved without any JVM parameter with Burningwave Core reflection components that thanks to a special driver work on all JDKs from 8. In this case you can also simply call the method org.burningwave.core.assembler.StaticComponentContainer.Modules.exportAllToAll()

try add jvm option - JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

Problem solved，thank you very much

try add jvm option - JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

Problem solved，thank you very much

How do it in Idea?

just use spring-core cglib,do not need to change code:

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
    </dependency>

import org.springframework.cglib.proxy.Enhancer;

try add jvm option - JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

Problem solved，thank you very much

Hi - Can you please where and how did you added these jvm options? I am using maven, spring boot latest versions, while migrating to jdk 17 i am getting InaccessibleObjectException, please advise. Thanks,

尝试添加 JVM 选项- JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

问题解决了，非常感谢

嗨 - 您能否请问您在哪里以及如何添加这些 jvm 选项？我正在使用 maven，Spring 启动最新版本，在迁移到 jdk 17 时，我遇到了无法访问的对象异常，请告知。谢谢

网上一大把

https://blog.51cto.com/Saintmm/5573298

For those unable to migrate to ByteBuddy easily, Spring Framework maintains patches for cglib that include compatibility for Java 17, you could do a similar thing and embed cglib into your sources:
https://github.com/spring-projects/spring-framework/tree/main/spring-core/src/main/java/org/springframework/cglib

I have replace cglib to the one embeded in spring framework, but the issue still occurs:

org.springframework.cglib.core.CodeGenerationException: java.lang.reflect.InaccessibleObjectException-->Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @385e9564 at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:598) ~[spring-core-5.3.23.jar:5.3.23] at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363) ~[spring-core-5.3.23.jar:5.3.23] at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110) ~[spring-core-5.3.23.jar:5.3.23] at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108) ~[spring-core-5.3.23.jar:5.3.23]

Hi, did you get this working? Please advise how did you solved this issue?

I seem to have found the answer, it works fine on spring-core-6.0.15 and the key to the fix lies in this patch.

spring-projects/spring-framework#28699

IntelliJ top bar -> Run -> Edit Configurations -> Modify options -> Add VM options -> Add the below option.

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

Add the above JVM option to your classes that use CGLIB. This should basically unlock reflection access on certain paths.

This error is caused by the module system introduced in Java 9 and later. It indicates that CGLIB tried to access the defineClass method of Java's ClassLoader class, but this method is not accessible.

Specifically, Java's module system restricts reflection access to certain packages or classes by default, and InaccessibleObjectException can be raised when a library such as CGLIB tries to access a restricted method.

It need to make reflection access unrestricted by default on certain paths. Therefore, add the following JVM option.

• JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

not working at all

try add jvm option - JVM_OPTS= --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED

This worked for me, thanks!