The login.config file is usually auto-detected by scanning the applications classpath via the ClassLoader. If the login.config files happens to be in a directory hierarchy that has a "" is a special character in URLs that is a surrogate for a space. Somewhere in the configuration detection process the "+" gets replaced by a space and then the file cannot be found any more. E.g. "/home/user/one+two/login.config" will get "/home/user/one two/login.config".