IKED signal 6 (Aborted) received

We have this issue with our Fortigate. After crashing iked we can't login to WWW interface and all IPSec tunnels are down. Is any idea why this happens? For fixing this issue need to restart iked and httpsd process or reboot device. P.S./ The CPU isn't overloaded and memory usage around 33% 816: 2018-06-16 04:53:33 <03432> firmware FortiGate-200B v5.2.13,build0762b762,171212 (GA) (Release) 817: 2018-06-16 04:53:33 <03432> application iked 818: 2018-06-16 04:53:33 <03432> *** signal 6 (Aborted) received *** 819: 2018-06-16 04:53:33 <03432> Register dump: 820: 2018-06-16 04:53:33 <03432> EAX: 00000000   EBX: 00000d68   ECX: 00000006    EDX: 40248ff4 821: 2018-06-16 04:53:33 <03432> ESI: 00000d68   EDI: ffffffc8   EBP: bffff658    ESP: bfffee8c 822: 2018-06-16 04:53:33 <03432> EIP: 40001012   EFLAGS: 00000246 823: 2018-06-16 04:53:33 <03432> CS: 0073   DS: 007b   ES: 007b   FS: 0000   GS: 0033   SS: 007b 824: 2018-06-16 04:53:33 <03432> Trap: 00000000   Error: 00000000   OldMask: 00000000 825: 2018-06-16 04:53:33 <03432> ESP/signal: bfffee8c   CR2: 00000000 826: 2018-06-16 04:53:33 <03432> Backtrace: 827: 2018-06-16 04:53:33 <03432> [0x40001012] => /fortidev4/lib/ld-linux.so.2  liboffset 00001012 828: 2018-06-16 04:53:33 <03432> [0x400d9058] => ../lib/libc.so.6 (gsignal+0x000000a8) liboffset  829: 2018-06-16 04:53:33 0002e058 830: 2018-06-16 04:53:33 <03432> [0x400da843] => ../lib/libc.so.6 (abort+0x00000143) liboffset 0002f843 831: 2018-06-16 04:53:33 <03432> [0x40116aa5] => ../lib/libc.so.6  liboffset 0006baa5 832: 2018-06-16 04:53:33 <03432> [0x4011d1d2] => ../lib/libc.so.6  liboffset 000721d2 833: 2018-06-16 04:53:33 <03432> [0x085fd855] => /bin/iked   834: 2018-06-16 04:53:33 <03432> [0x0859f28d] => /bin/iked   835: 2018-06-16 04:53:33 <03432> [0x0859f22b] => /bin/iked   836: 2018-06-16 04:53:33 <03432> [0x0859f36e] => /bin/iked   837: 2018-06-16 04:53:33 <03432> [0x0859f46a] => /bin/iked   838: 2018-06-16 04:53:33 <03432> [0x085fc305] => /bin/iked   839: 2018-06-16 04:53:33 <03432> [0x085bbb3b] => /bin/iked   840: 2018-06-16 04:53:33 <03432> [0x080759ca] => /bin/iked   841: 2018-06-16 04:53:33 <03432> [0x080754fc] => /bin/iked   842: 2018-06-16 04:53:33 <03432> [0x08073de0] => /bin/iked   843: 2018-06-16 04:53:33 <03432> [0x08075233] => /bin/iked   844: 2018-06-16 04:53:33 <03432> [0x080735cd] => /bin/iked   845: 2018-06-16 04:53:33 <03432> [0x400c43e5] => ../lib/libc.so.6 (__libc_start_main+0x000000f5)  846: 2018-06-16 04:53:33 liboffset 000193e5 847: 2018-06-16 04:53:33 <03432> [0x08073651] => /bin/iked