java.lang.SecurityException: sealing violation:

Question

I am using GWT for my Java application. When I try to run it as web application, I get the following error:

java.lang.SecurityException: sealing viola

Answer 1

It means the package is sealed and you tried to load another jar also containing the package.

See Sealing Packages within a JAR File.

Answer 2

Your current exception shows that you are using Jetty in your project. Possible problem might be that you have this jar available twice in your classpath.

Answer 3

Goto your jar file,you will see .MF file.Open it.You will find Sealed:true. Edit it, make it false.Over.