For example we see this trace in the log when we call the finder with null parameter (due to unchecked null input from user): Caused by: groovy.lang.MissingMethodException: No signature of method: static PendingEmailConfirmation.findByConfirmationToken() is applicable for argument types: (null) values: {null} at groovy.lang.MetaClassImpl.invokeStaticMethod(MetaClassImpl.java:738) This should of course not happen, it should just fail to find one, unless there is one with a null token.