breaks jsp compilation | 易学教程

问题

I'm working on a project with a web-GUI using jsp. For development I use a jetty server run through IntelliJ IDEA. A while ago I had a seemingly random error regarding JSP compilation:

apr 21, 2016 9:23:53 AM org.apache.jasper.servlet.JspServletWrapper loadTagFile
SEVERE: PWC6354: Error occurred while compiling JSP files.  
java.lang.NullPointerException
    at sun.reflect.misc.ReflectUtil.checkPackageAccess(ReflectUtil.java:164)
    at sun.reflect.misc.ReflectUtil.isPackageAccessible(ReflectUtil.java:195)
    at java.beans.Introspector.getBeanInfo(Introspector.java:164)
    at org.apache.jasper.compiler.Generator$TagHandlerInfo.<init>(Generator.java:3902)
    at org.apache.jasper.compiler.Generator$GenerateVisitor.getTagHandlerInfo(Generator.java:2241)
    at org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1640)
    at org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1501)
    at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2302)
    at org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2352)
    at org.apache.jasper.compiler.Generator$GenerateVisitor.generateJspFragment(Generator.java:3196)
    at org.apache.jasper.compiler.Generator$GenerateVisitor.generateCustomDoTag(Generator.java:2546)
    at org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1723)
    at org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1501)

The first time around I got rid of it by invalidating caches and rebuilding my project in IDEA. Since that, I have had a couple of concrete changes creating this error:

When upgrading spring security from 3.2.8.RELEASE to 4.0.3.RELEASE (!)
When adding a   in my jsp, like this:

<label>Monkey   </label>

Now I'm quite stuck. I find the causes for this to happen strange, and the stacktrace includes jetty, springsecurity (filter) and jasper, as well as internal java calls. I need to narrow my search, but I don't know where to start. Any ideas?

This error also seems to occur seemingly at random. I've had team members that had to reinstall IntelliJ due to this.