App crash when download

W/WM-WorkSpec( 639): Backoff delay duration less than minimum value
D/ConnectivityManager( 639): requestNetwork; CallingUid : 10487, CallingPid : 639, PackageName : com.example.ghmc
D/DownloadWorker( 639): DownloadWorker{url=http://digitalraiz.com/projects/geo_tagginging_ghmc/api/TotalExcel?user_id=3044&date=2021-06-26&action=total,filename=null,savedDir=/storage/emulated/0/GHMC/,header=,isResume=false
D/DownloadWorker( 639): Update notification: {notificationId: 3, title: http://digitalraiz.com/projects/geo_tagginging_ghmc/api/TotalExcel?user_id=3044&date=2021-06-26&action=total, status: 2, progress: 0}
D/DownloadWorker( 639): Open connection to http://digitalraiz.com/projects/geo_tagginging_ghmc/api/TotalExcel?user_id=3044&date=2021-06-26&action=total
I/System.out( 639): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 639): (HTTPLog)-Static: isSBSettingEnabled false
D/DownloadWorker( 639): Content-Type = application/vnd.ms-excel
D/DownloadWorker( 639): Content-Length = -1
D/DownloadWorker( 639): Charset = null
D/DownloadWorker( 639): Content-Disposition = attachment;filename="vehiclelist.xls"
D/DownloadWorker( 639): fileName = vehiclelist.xls
D/DownloadWorker( 639): Update too frequently!!!!, but it is the final update, we should sleep a second to ensure the update call can be processed
I/flutter ( 639): Fatal: could not find callback