subsonic 3.1 null pointer exception after clicking on cover

[vaxmaster]

This bug is new in 3.1 Version.

Error

Subsonic encountered an internal error. You can report this error in the Subsonic Forum. Please include the information below.
Exception java.lang.NullPointerException
Message null
Java version Sun Microsystems Inc. 1.6.0-beta2
Operating system SunOS 5.11
Server Apache Tomcat/6.0.10
Memory Used 276 of 943 MB
Stack trace java.lang.NullPointerException at net.sourceforge.subsonic.domain.MusicFile.getChildren(MusicFile.java:208) at net.sourceforge.subsonic.controller.MainController.handleRequestInternal(MainController.java:53) at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:153) at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:45) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:820) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:755) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:396) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:350) at javax.servlet.http.HttpServlet.service(HttpServlet.java:690) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:264) at org.acegisecurity.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:107) at org.acegisecurity.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:72) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:110) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.wrapper.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:81) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.ui.basicauth.BasicProcessingFilter.doFilter(BasicProcessingFilter.java:178) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:217) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.ui.logout.LogoutFilter.doFilter(LogoutFilter.java:106) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:229) at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274) at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:148) at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at net.sourceforge.subsonic.filter.RequestEncodingFilter.doFilter(RequestEncodingFilter.java:25) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at net.sourceforge.subsonic.filter.ParameterDecodingFilter.doFilter(ParameterDecodingFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at net.sourceforge.subsonic.filter.BootstrapVerificationFilter.doFilter(BootstrapVerificationFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216) at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190) at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:283) at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:767) at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:697) at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:889) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:686) at java.lang.Thread.run(Thread.java:626)

[linuxman]

This happens when the directory where the mp3 files are located you are trying to add the album art doesn't have proper permissions for the user subsonic is running under to write the Folder.jpg file. Just add everyone write access to that folder or the specific user write access and it will work.