java.lang.VerifyError can be the result when you have compiled against a different library than you are using at runtime.
For example, this happened to me when trying to run a program that was compiled against Xerces 1, but Xerces 2 was found on the classpath. The required classes (in
org.apache.* namespace) were found at runtime, so
ClassNotFoundException was not the result. There had been changes to the classes and methods, so that the method signatures found at runtime did not match what was there at compile-time.
Normally, the compiler will flag problems where method signatures do not match. The JVM will verify the bytecode again when the class is loaded, and throws
VerifyError when the bytecode is trying to do something that should not be allowed — e.g. calling a method that returns
String and then stores that return value in a field that holds a