Web Part Error: Sandboxed code execution request failed. Correlation ID: 8a4bf29e-672a-b005-39f1-6785a46241a9.

Error Details:
[SPUserCodeExecutionPipelineFailedException: Sandboxed code execution request failed.]
  at Microsoft.SharePoint.UserCode.SPUserCodeExecutionManager.Execute(Type userCodeWrapperType, SPSite site, SPUserCodeExecutionContext executionContext, SPUserCodeActivationSiteInfo activationSite)
  at Microsoft.SharePoint.UserCode.SPUserCodeExecutionManager.Execute(Type userCodeWrapperType, SPSite site, SPUserCodeExecutionContext executionContext)
  at Microsoft.SharePoint.UserCode.SPUserCodeWebPartRemoteExecutionHelper.<>c__DisplayClassa.b__9()
  at Microsoft.SharePoint.Utilities.SecurityContext.RunAsProcess(CodeToRunElevated secureCode)
  at Microsoft.SharePoint.UserCode.SPUserCodeWebPartRemoteExecutionHelper.ExecuteRequestInSandBox(HttpContext context, SPWeb web, SPWebPartManager manager, SPUserCodeWebPart userCodeWebPart)

[RemotingException: Server encountered an internal error. For more information, turn off customErrors in the server's .config file.]
 
 Server stack trace:
 
 
 Exception rethrown at [0]:
  at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
  at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
  at Microsoft.SharePoint.Administration.ISPUserCodeExecutionHostProxy.Execute(Type userCodeWrapperType, Guid siteCollectionId, SPUserToken userToken, String affinityBucketName, SPUserCodeExecutionContext executionContext)
  at Microsoft.SharePoint.UserCode.SPUserCodeExecutionManager.Execute(Type userCodeWrapperType, SPSite site, SPUserCodeExecutionContext executionContext, SPUserCodeActivationSiteInfo activationSite)