Application: dolphin (18.08.3)
 (Compiled from sources)
Qt Version: 5.11.2
Frameworks Version: 5.52.0
Operating System: Linux 4.19.2-gentoo x86_64
Distribution: "Gentoo Base System release 2.6"

-- Information about the crash:
- What I was doing when the application crashed:
- Open Dolphin at home dir
- Press "v" on keyboard -> Dolphin selected "Video" dir
- Press "Enter" on keyboard to enter the dir
- Dolphin crashed

Reproducable: Always

- lmdb-0.9.22

The crash can be reproduced every time.

-- Backtrace:
Application: Dolphin (dolphin), signal: Aborted
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fd9d807f380 (LWP 4704))]

Thread 5 (Thread 0x7fd9ccd17700 (LWP 4708)):
#0  0x00007fd9e05f3c4b in poll () from /lib64/libc.so.6
#1  0x00007fd9dc08054e in ?? () from /usr/lib64/libglib-2.0.so.0
#2  0x00007fd9dc08066c in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#3  0x00007fd9de7a591b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#4  0x00007fd9de753afb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#5  0x00007fd9de5c20c6 in QThread::exec() () from /usr/lib64/libQt5Core.so.5
#6  0x00007fd9de5cb52e in ?? () from /usr/lib64/libQt5Core.so.5
#7  0x00007fd9dcf043e3 in start_thread () from /lib64/libpthread.so.0
#8  0x00007fd9e05ffcdf in clone () from /lib64/libc.so.6

Thread 4 (Thread 0x7fd9ce428700 (LWP 4707)):
#0  0x00007fd9dcf0b1fc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007fd9d521665b in ?? () from /usr/lib64/dri/nouveau_dri.so
#2  0x00007fd9d5216397 in ?? () from /usr/lib64/dri/nouveau_dri.so
#3  0x00007fd9dcf043e3 in start_thread () from /lib64/libpthread.so.0
#4  0x00007fd9e05ffcdf in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x7fd9d698f700 (LWP 4706)):
#0  0x00007fd9e05f3c4b in poll () from /lib64/libc.so.6
#1  0x00007fd9dc08054e in ?? () from /usr/lib64/libglib-2.0.so.0
#2  0x00007fd9dc08066c in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#3  0x00007fd9de7a591b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#4  0x00007fd9de753afb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#5  0x00007fd9de5c20c6 in QThread::exec() () from /usr/lib64/libQt5Core.so.5
#6  0x00007fd9de9f3585 in ?? () from /usr/lib64/libQt5DBus.so.5
#7  0x00007fd9de5cb52e in ?? () from /usr/lib64/libQt5Core.so.5
#8  0x00007fd9dcf043e3 in start_thread () from /lib64/libpthread.so.0
#9  0x00007fd9e05ffcdf in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7fd9d781f700 (LWP 4705)):
#0  0x00007fd9e05f3c4b in poll () from /lib64/libc.so.6
#1  0x00007fd9dba07d5f in ?? () from /usr/lib64/libxcb.so.1
#2  0x00007fd9dba09a1a in xcb_wait_for_event () from /usr/lib64/libxcb.so.1
#3  0x00007fd9d7b472f9 in ?? () from /usr/lib64/libQt5XcbQpa.so.5
#4  0x00007fd9de5cb52e in ?? () from /usr/lib64/libQt5Core.so.5
#5  0x00007fd9dcf043e3 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fd9e05ffcdf in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7fd9d807f380 (LWP 4704)):
[KCrash Handler]
#6  0x00007fd9e052e82b in raise () from /lib64/libc.so.6
#7  0x00007fd9e0517515 in abort () from /lib64/libc.so.6
#8  0x00007fd9db9ec7c2 in mdb_assert_fail (env=0x55bb8aac7a80, expr_txt=expr_txt@entry=0x7fd9db9ef099 "i > 0", func=func@entry=0x7fd9db9ef930 <__func__.8372> "mdb_page_search_root", line=line@entry=5487, file=0x7fd9db9ef010 "mdb.c") at mdb.c:1542
#9  0x00007fd9db9e2f15 in mdb_page_search_root (mc=mc@entry=0x7ffd1a8befe0, key=key@entry=0x7ffd1a8bf3a0, flags=flags@entry=0) at mdb.c:5516
#10 0x00007fd9db9e3094 in mdb_page_search (mc=mc@entry=0x7ffd1a8befe0, key=key@entry=0x7ffd1a8bf3a0, flags=flags@entry=0) at mdb.c:5633
#11 0x00007fd9db9e37d5 in mdb_cursor_set (mc=mc@entry=0x7ffd1a8befe0, key=key@entry=0x7ffd1a8bf3a0, data=data@entry=0x7ffd1a8bf3b0, op=op@entry=MDB_SET, exactp=exactp@entry=0x7ffd1a8befdc) at mdb.c:6104
#12 0x00007fd9db9e3e51 in mdb_get (txn=<optimized out>, dbi=<optimized out>, key=0x7ffd1a8bf3a0, data=0x7ffd1a8bf3b0) at mdb.c:5762
#13 0x00007fd9dd9c19a8 in Baloo::DocumentDataDB::get(unsigned long long) () from /usr/lib64/libKF5BalooEngine.so.5
#14 0x00007fd9dd9db611 in Baloo::Transaction::documentData(unsigned long long) const () from /usr/lib64/libKF5BalooEngine.so.5
#15 0x00007fd9dfe066c3 in Baloo::File::load() () from /usr/lib64/libKF5Baloo.so.5
#16 0x00007fd9e000dac8 in ?? () from /usr/lib64/libKF5BalooWidgets.so.5
#17 0x00007fd9de77df72 in QObject::event(QEvent*) () from /usr/lib64/libQt5Core.so.5
#18 0x00007fd9df0bb755 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQt5Widgets.so.5
#19 0x00007fd9df0c3240 in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQt5Widgets.so.5
#20 0x00007fd9de754bb5 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib64/libQt5Core.so.5
#21 0x00007fd9de757e56 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib64/libQt5Core.so.5
#22 0x00007fd9de7a5b63 in ?? () from /usr/lib64/libQt5Core.so.5
#23 0x00007fd9dc08031d in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0
#24 0x00007fd9dc0805d8 in ?? () from /usr/lib64/libglib-2.0.so.0
#25 0x00007fd9dc08066c in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#26 0x00007fd9de7a5903 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#27 0x00007fd9d7bd95f1 in ?? () from /usr/lib64/libQt5XcbQpa.so.5
#28 0x00007fd9de753afb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#29 0x00007fd9de75bcef in QCoreApplication::exec() () from /usr/lib64/libQt5Core.so.5
#30 0x00007fd9e070bf6b in kdemain () from /usr/lib64/libkdeinit5_dolphin.so
#31 0x00007fd9e05194cb in __libc_start_main () from /lib64/libc.so.6
#32 0x000055bb8939508a in _start ()
[Inferior 1 (process 4704) detached]

Reported using DrKonqi