Not super sure how it happened but I signed a document successfully and closed the document+okular. I got such a crash but ignored it because I was closing it anyway.

Opened another okular to sign a second one and I get the following error: "All your signing certificates are either not valid yet or are past their validity date.". And when I close okular I always get the following crash.

Application: Okular (okular), signal: Segmentation fault
Content of s_kcrashErrorMessage: std::unique_ptr<char []> = {get() = 0x0}
[KCrash Handler]
#5  0x00007f09dd2a2c67 in pthread_mutex_trylock () at /usr/lib/libc.so.6
#6  0x00007f09c91f1502 in NativeLockMutex(void*) () at /usr/lib/libpkcs11-dnie.so
#7  0x00007f09c91e75e7 in C_CloseAllSessions () at /usr/lib/libpkcs11-dnie.so
#8  0x00007f09a6123b3f in PK11_FreeSlot () at /usr/lib/libnss3.so
#9  0x00007f09a6126bfd in SECMOD_DestroyModule () at /usr/lib/libnss3.so
#10 0x00007f09a60eb3c6 in  () at /usr/lib/libnss3.so
#11 0x00007f09a60ec0e1 in NSS_Shutdown () at /usr/lib/libnss3.so
#12 0x00007f09a6583ecd in shutdownNss() () at /home/apol/devel/frameworks/poppler/poppler/SignatureHandler.cc:212
#13 0x00007f09dd254445 in  () at /usr/lib/libc.so.6
#14 0x00007f09dd2545b0 in  () at /usr/lib/libc.so.6
#15 0x00007f09dd23c797 in  () at /usr/lib/libc.so.6
#16 0x00007f09dd23c84a in __libc_start_main () at /usr/lib/libc.so.6
#17 0x0000563b43a3aca5 in _start ()
[Inferior 1 (process 687672) detached]