Background is I want to take a photo from mobile phone using ‘Take picture’ in web camera in nano flow. The application is deployed on AWS EC2 with Ubuntu. It’s work well when using laptop, but when using Ipad or Iphone, it doesn’t work. The error log on server said that: WARNING - Core: Failed cluster management action: cleanup orphaned files. java.lang.NullPointerException: null at scala.collection.StringOps$.forall$extension(StringOps.scala:1050) at com.mendix.filedocumentprocessor.UnreferencedFileCleanup.$anonfun$retrieveReferencedFiles$1(UnreferencedFileCleanup.scala$ at com.mendix.filedocumentprocessor.UnreferencedFileCleanup.$anonfun$retrieveReferencedFiles$1$adapted(UnreferencedFileClean$ at scala.collection.immutable.List.filter(List.scala:515) at scala.collection.immutable.List.filter(List.scala:79) at com.mendix.filedocumentprocessor.UnreferencedFileCleanup.retrieveReferencedFiles(UnreferencedFileCleanup.scala:171) at com.mendix.filedocumentprocessor.UnreferencedFileCleanup.deleteUnreferencedFiles(UnreferencedFileCleanup.scala:135) at com.mendix.filedocumentprocessor.UnreferencedFileCleanup.cleanup$1(UnreferencedFileCleanup.scala:100) at com.mendix.filedocumentprocessor.UnreferencedFileCleanup.cleanUpOrphans(UnreferencedFileCleanup.scala:104) at com.mendix.basis.action.system.ClusterManagementAction$.$anonfun$cleanupOrphanFiles$2(ClusterManagementAction.scala:76) at com.mendix.basis.action.system.ClusterManagementAction$.$anonfun$cleanupOrphanFiles$2$adapted(ClusterManagementAction.sca$ at com.mendix.basis.action.system.ClusterManagementAction$$anon$1.execute(ClusterManagementAction.scala:24) How to fix the problem and what is the cause of this problem?