Maven compilation issue with Java 9

Just add this

<forceJavacCompilerUse>true</forceJavacCompilerUse>

to your maven compiler build plugin in your POM and you'll see all the javac errors! Source with more details

UPDATE

Most of the time this error seems to occur, when the compiler is trying to report a compilation error, but it blows up in the process. So far mainly two approach helped to resolve these issues:

• Disable annotation processing by using -proc:none compiler argument (it seems like that annotation processing can upset the compiler, so if you are not meant to use any, this is a free win).
• Debug the compiler using a conditional breakpoint and walk the stack until a compiler error message can be found, and then fix that error...

ORGINAL SOLUTION

After lots of trial and error I was able to work around/fix this problem locally, my approach in the end was the following:

• I had an assumption that maybe the dependencies are somehow interfering with the build result, so I started to comment out Maven <dependency> entries in the failing module's POM.
• the build then started to fail, but it did so with the expected cannot find symbol and similar compilation errors instead of the unhelpful AssertionError failure
• it turned out that there was one particular dependency that triggered this AssertionError.
• After code analysis, I couldn't determine any good reason why that dependency would cause problems, so I started to look at the transitive dependencies
• I then used the same approach as before, but instead of uncommenting the faulty dependency, I've inserted all of its transitive dependencies into the POM
• the build again failed, and after lots and lots of testing it turned out that I could trigger the AssertionError when both io.vavr:vavr:0.9.0:compile and javax.servlet:servlet-api:3.0.1:test were included in the dependency graph

It is still beyond me how a test scoped dependency could have any effect on the project's compilation... It also turned out that javax.servlet:servlet-api:3.0.1:provided was already amongst the dependencies of the failing module, and the test scoped dependency wasn't actually used for anything.

In the end I just removed the incorrectly defined test scoped servlet-api dependency from the bug triggering module and suddenly Maven was able to compile the previously failing module.

I'm fairly sure that this is a very obscure answer to a very obscure question in the first place, but hopefully my approach will be of use for someone else.

I got the same error on java 11. Adding jaxb api dependency to the pom solved my issue.