I got the same error with Win 7 / JBoss 6.0.0.20100721-M4 / Struts 2.2.1.

The error occures in the xwork-lib. I also tried different xwork version, same result.

In my case, first time xworks tries to load "struts-default.xml"

xwork gets from struts2 this url:

vfs:/D:/jboss-6.0.0.M4/server/default/deploy/LuZie.ear/WEB.war/WEB-INF/lib/struts2-core-2.2.1.jar/struts-default.xml

Then tries to load it:

URL url = URLUtil.normalizeToFileProtocol(fileUrl);

if (url != null) {
     JarFile jarFile = new JarFile(new File(url.getPath().replaceAll("%20", " ")));
     ZipEntry entry = jarFile.getEntry(fileNameInJar);
     return new JarEntryRevision(jarFileName.toString(), fileNameInJar, entry.getTime());
}

url is = "vfs:/D:/jboss-6.0.0.M4/server/default/deploy/LuZie.ear/WEB.war/WEB-INF/lib/struts2-core-2.2.1"

This fails!