Nexus 10, Android 4.4.4, FF 33.0, locale English I can't open downloaded *.zip file because I have only one installed application which open it. The problem is completelly solved when I install some second application for this kind of file (*.zip in my case). It happens because in first case FF launches the file directly, but in second case - thru Resolver activity. Test 1: failed 11-07 23:49:54.912: I/ActivityManager(452): START u0 {act=android.intent.action.VIEW dat=file:///storage/emulated/0/Download/libffmpeg.neon.1.7.31.zip flg=0x4000000} from pid 2416 11-07 23:49:54.927: E/GeckoConsole(2416): Error: openDownload() [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIFile.launch]" nsresult: "0x80004005 (NS_ERROR_FAILURE)" location: "JS frame :: chrome://browser/content/aboutDownloads.js :: dl_openDownload/< :: line 467" data: no] Test 2: passed 11-07 23:51:00.472: D/GeckoHealthRec(2416): Recording session end: P 11-07 23:51:00.472: I/ActivityManager(452): START u0 {act=android.intent.action.VIEW dat=file:///storage/emulated/0/Download/libffmpeg.neon.1.7.31.zip typ=application/zip flg=0x4000000 cmp=android/com.android.internal.app.ResolverActivity} from pid 2416 11-07 23:51:00.482: I/ActivityManager(452): Start proc system:ui for activity android/com.android.internal.app.ResolverActivity: pid=10356 uid=1000 gids={41000, 1028, 1015, 3002, 3001, 3003} 11-07 23:51:00.487: V/GeckoHealthRec(2416): Recorded session entry for env 12, current is 12 11-07 23:51:00.487: D/GeckoSessInfo(2416): Recording session done: 1415397053051 11-07 23:51:00.492: D/GeckoBrowserProvider(2416): Expiring history. 11-07 23:51:00.492: D/GeckoBrowserProvider(2416): Expiring thumbnails. 11-07 23:51:00.507: I/GeckoHealth(2416): firefox :: HealthReportBroadcastService :: Registering HealthReportPruneService. 11-07 23:51:00.507: I/GeckoHealth(2416): firefox :: BackgroundService :: Setting inexact repeating alarm for interval 86400000