Assertion failure: !dl (Can't call RemoveDownload on a download in progress!), at c:/mozilla/mozilla-inbound/toolkit/components/downloads/nsDownloadManager.cpp:1917 STR: 1. start a download 2. pause the download in the middle 3. open the history sidebar by Last Visited 4. Forget about this page on the download history entry I think the DM receives onDeleteURI and tries to remove the download even if it's in-progress.

I've hit this one too - here's my backtrace: #0 0xb77b8424 in __kernel_vsyscall () #1 0xb755ac16 in nanosleep () at ../sysdeps/unix/syscall-template.S:82 #2 0xb755aa0f in __sleep (seconds=0) at ../sysdeps/unix/sysv/linux/sleep.c:138 #3 0xb2f40fba in ah_crap_handler (signum=11) at /media/Projects/mozilla/fx-team/toolkit/xre/nsSigHandlers.cpp:88 #4 0xb2f4a412 in nsProfileLock::FatalSignalHandler (signo=11, info=0xbf8e675c, context=0xbf8e67dc) at /media/Projects/mozilla/objdir-fx-team-patches/toolkit/profile/nsProfileLock.cpp:190 #5 <signal handler called> #6 0xb41aab41 in nsDownloadManager::RemoveDownload (this=0xa6bfb3a0, aGUID=...) at /media/Projects/mozilla/fx-team/toolkit/components/downloads/nsDownloadManager.cpp:1860 #7 0xb419f5ba in nsDownloadManager::RemoveDownloadsForURI (this=0xa6bfb3a0, aStatement=0xa3ef6d80, aURI=0x9c6fe280) at /media/Projects/mozilla/fx-team/toolkit/components/downloads/nsDownloadManager.cpp:274 #8 0xb41ace61 in nsDownloadManager::OnDeleteURI (this=0xa6bfb3a0, aURI=0x9c6fe280, aGUID=..., aReason=0) at /media/Projects/mozilla/fx-team/toolkit/components/downloads/nsDownloadManager.cpp:2283 #9 0xb438adc7 in nsNavHistory::NotifyOnPageExpired (this=0xb72f4da0, aURI=0x9c6fe280, aVisitTime=1360080909534617, aWholeEntry=true, aGUID=..., aReason=0, aTransitionType=7) at /media/Projects/mozilla/fx-team/toolkit/components/places/nsNavHistory.cpp:3629 #10 0xb43dd389 in mozilla::places::(anonymous namespace)::NotifyVisitRemoval (aEntry=0xa15afc5c, aHistory=0xb72f4da0) at /media/Projects/mozilla/fx-team/toolkit/components/places/History.cpp:1452 #11 0xb43e6b33 in nsTHashtable<mozilla::places::PlaceHashKey>::s_EnumStub (table=0x948d64cc, entry=0xa15afc5c, number=1, arg=0xbf8e6e78) at ../../../dist/include/nsTHashtable.h:486 #12 0xb4900538 in PL_DHashTableEnumerate (table=0x948d64cc, etor=0xb43e6b16 <nsTHashtable<mozilla::places::PlaceHashKey>::s_EnumStub(PLDHashTable*, PLDHashEntryHdr*, unsigned int, void*)>, arg=0xbf8e6e78) at /media/Projects/mozilla/objdir-fx-team-patches/xpcom/build/pldhash.cpp:717 #13 0xb43e57c6 in nsTHashtable<mozilla::places::PlaceHashKey>::EnumerateEntries (this=0x948d64cc, enumFunc=0xb43dd212 <mozilla::places::(anonymous namespace)::NotifyVisitRemoval(mozilla::places::PlaceHashKey*, void*)>, userArg=0xb72f4da0) at ../../../dist/include/nsTHashtable.h:237 #14 0xb43dd542 in mozilla::places::(anonymous namespace)::NotifyRemoveVisits::Run (this=0x948d64c0) at /media/Projects/mozilla/fx-team/toolkit/components/places/History.cpp:1492 #15 0xb496869d in nsThread::ProcessNextEvent (this=0xb72fd240, mayWait=false, result=0xbf8e6f8f) at /media/Projects/mozilla/fx-team/xpcom/threads/nsThread.cpp:627 #16 0xb48fe126 in NS_ProcessNextEvent_P (thread=0xb72fd240, mayWait=false) at /media/Projects/mozilla/objdir-fx-team-patches/xpcom/build/nsThreadUtils.cpp:238 #17 0xb45c0c2a in mozilla::ipc::MessagePump::Run (this=0xb72c23a0, aDelegate=0xb721a980) at /media/Projects/mozilla/fx-team/ipc/glue/MessagePump.cpp:82 #18 0xb49b99b8 in MessageLoop::RunInternal (this=0xb721a980) at /media/Projects/mozilla/fx-team/ipc/chromium/src/base/message_loop.cc:215 #19 0xb49b9943 in MessageLoop::RunHandler (this=0xb721a980) at /media/Projects/mozilla/fx-team/ipc/chromium/src/base/message_loop.cc:208 #20 0xb49b9925 in MessageLoop::Run (this=0xb721a980) at /media/Projects/mozilla/fx-team/ipc/chromium/src/base/message_loop.cc:182 #21 0xb445253d in nsBaseAppShell::Run (this=0xad202330) at /media/Projects/mozilla/fx-team/widget/xpwidgets/nsBaseAppShell.cpp:163 #22 0xb419a056 in nsAppStartup::Run (this=0xad21c0a0) at /media/Projects/mozilla/fx-team/toolkit/components/startup/nsAppStartup.cpp:288 #23 0xb2f37460 in XREMain::XRE_mainRun (this=0xbf8e7320) at /media/Projects/mozilla/fx-team/toolkit/xre/nsAppRunner.cpp:3823 #24 0xb2f37765 in XREMain::XRE_main (this=0xbf8e7320, argc=1, argv=0xbf8e8644, aAppData=0xbf8e7454) at /media/Projects/mozilla/fx-team/toolkit/xre/nsAppRunner.cpp:3890 #25 0xb2f379a9 in XRE_main (argc=1, argv=0xbf8e8644, aAppData=0xbf8e7454, aFlags=0) at /media/Projects/mozilla/fx-team/toolkit/xre/nsAppRunner.cpp:4093 #26 0x0804a716 in do_main (argc=1, argv=0xbf8e8644, xreDirectory=0xb722a280) at /media/Projects/mozilla/fx-team/browser/app/nsBrowserApp.cpp:185 #27 0x0804ab6d in main (argc=1, argv=0xbf8e8644) at /media/Projects/mozilla/fx-team/browser/app/nsBrowserApp.cpp:377