SUMMARY
Okular crashes every time an attempt is made to open a file either by passing the filename on the command line or via the File menu.

STEPS TO REPRODUCE
1. Locate the okular binary
2. execute the okular binary
3. open a file either via the command line or File menu

OBSERVED RESULT
Okular crashes 

EXPECTED RESULT
okular to open a document without crashing


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.18.2
KDE Frameworks Version: 5.67.0
Qt Version: 5.15.0
Kernel: 5.5.7

ADDITIONAL INFORMATION
The crash is always happening in okularparts.so (See backtrace below). This issue started about 2 weeks ago. I thereafter compiled okular and replace my compiled version of okularparts.so with the packaged one and everything worked ok again. After a subsequent update via pacman -Su i noticed that the problem is back! causing to to again replace okularparts.so with my own compiled version.

backtrace:

Application: Okular (okular), signal: Bus error
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7ff7bda33840 (LWP 3778))]

Thread 7 (Thread 0x7ff7acfdd700 (LWP 3786)):
#0  0x00007ff7c0a7dcf5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007ff7aee64e1c in ?? () from /usr/lib/dri/i965_dri.so
#2  0x00007ff7aee64a18 in ?? () from /usr/lib/dri/i965_dri.so
#3  0x00007ff7c0a7746f in start_thread () from /usr/lib/libpthread.so.0
#4  0x00007ff7c15043d3 in clone () from /usr/lib/libc.so.6

Thread 6 (Thread 0x7ff7ad7de700 (LWP 3785)):
#0  0x00007ff7c0a7dcf5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007ff7aee64e1c in ?? () from /usr/lib/dri/i965_dri.so
#2  0x00007ff7aee64a18 in ?? () from /usr/lib/dri/i965_dri.so
#3  0x00007ff7c0a7746f in start_thread () from /usr/lib/libpthread.so.0
#4  0x00007ff7c15043d3 in clone () from /usr/lib/libc.so.6

Thread 5 (Thread 0x7ff7adfdf700 (LWP 3784)):
#0  0x00007ff7c0a7dcf5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007ff7aee64e1c in ?? () from /usr/lib/dri/i965_dri.so
#2  0x00007ff7aee64a18 in ?? () from /usr/lib/dri/i965_dri.so
#3  0x00007ff7c0a7746f in start_thread () from /usr/lib/libpthread.so.0
#4  0x00007ff7c15043d3 in clone () from /usr/lib/libc.so.6

Thread 4 (Thread 0x7ff7ae7e0700 (LWP 3783)):
#0  0x00007ff7c0a7dcf5 in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007ff7aee64e1c in ?? () from /usr/lib/dri/i965_dri.so
#2  0x00007ff7aee64a18 in ?? () from /usr/lib/dri/i965_dri.so
#3  0x00007ff7c0a7746f in start_thread () from /usr/lib/libpthread.so.0
#4  0x00007ff7c15043d3 in clone () from /usr/lib/libc.so.6

Thread 3 (Thread 0x7ff7b6d8b700 (LWP 3780)):
#0  0x00007ff7bff43039 in g_source_ref () from /usr/lib/libglib-2.0.so.0
#1  0x00007ff7bff49cd9 in ?? () from /usr/lib/libglib-2.0.so.0
#2  0x00007ff7bff4afbb in g_main_context_prepare () from /usr/lib/libglib-2.0.so.0
#3  0x00007ff7bff4b6c6 in ?? () from /usr/lib/libglib-2.0.so.0
#4  0x00007ff7bff4b871 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#5  0x00007ff7c1abc28c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007ff7c1a60dbc in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#7  0x00007ff7c1881d02 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#8  0x00007ff7c1d13b38 in ?? () from /usr/lib/libQt5DBus.so.5
#9  0x00007ff7c1882e96 in ?? () from /usr/lib/libQt5Core.so.5
#10 0x00007ff7c0a7746f in start_thread () from /usr/lib/libpthread.so.0
#11 0x00007ff7c15043d3 in clone () from /usr/lib/libc.so.6

Thread 2 (Thread 0x7ff7bcbfc700 (LWP 3779)):
#0  0x00007ff7c14f9abf in poll () from /usr/lib/libc.so.6
#1  0x00007ff7c0cf863b in ?? () from /usr/lib/libxcb.so.1
#2  0x00007ff7c0cfa37b in xcb_wait_for_event () from /usr/lib/libxcb.so.1
#3  0x00007ff7bd59bf11 in ?? () from /usr/lib/libQt5XcbQpa.so.5
#4  0x00007ff7c1882e96 in ?? () from /usr/lib/libQt5Core.so.5
#5  0x00007ff7c0a7746f in start_thread () from /usr/lib/libpthread.so.0
#6  0x00007ff7c15043d3 in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0x7ff7bda33840 (LWP 3778)):
[KCrash Handler]
#6  0x00007ff7c1ae1ea2 in QJsonObject::initialize() () from /usr/lib/libQt5Core.so.5
#7  0x00007ff7b5a59ccf in Okular::Part::openFile() () from /usr/lib/qt/plugins/okularpart.so
#8  0x00007ff7c3279adf in ?? () from /usr/lib/libKF5Parts.so.5
#9  0x00007ff7c327aadf in KParts::ReadOnlyPart::openUrl(QUrl const&) () from /usr/lib/libKF5Parts.so.5
#10 0x00007ff7b5a49662 in Okular::Part::openUrl(QUrl const&, bool) () from /usr/lib/qt/plugins/okularpart.so
#11 0x0000558daee8a4de in ?? ()
#12 0x0000558daee8a768 in ?? ()
#13 0x0000558daee82f13 in ?? ()
#14 0x0000558daee82727 in ?? ()
#15 0x00007ff7c142c023 in __libc_start_main () from /usr/lib/libc.so.6
#16 0x0000558daee837ce in ?? ()
[Inferior 1 (process 3778) detached]