Troubleshooting Tip : How to troubleshoot application virtual wan link (VWL) crash

[darisandy]

Description	This article describes how to troubleshoot when getting an alert about an application VWL crash.
Scope	FortiGate.
Solution	The System Event log may show that the application VWL crashed. Example of the crash : diagnose debug crashlog read 16343: 2025-09-02 14:05:53 <27739> firmware FortiGate-200E v7.4.8,build2795b2795,250523 (GA.M) (Release) 16344: 2025-09-02 14:05:53 <27739> application vwl 16345: 2025-09-02 14:05:53 <27739> *** signal 6 (Aborted) received *** 16346: 2025-09-02 14:05:53 <27739> Register dump: 16347: 2025-09-02 14:05:53 <27739> RAX: 0000000000000000 RBX: 00007f55d5e45300 16348: 2025-09-02 14:05:53 <27739> RCX: ffffffffffffffff RDX: 0000000000000000 16349: 2025-09-02 14:05:53 <27739> R08: 0000000000000000 R09: 00007fffa4739870 16350: 2025-09-02 14:05:53 <27739> R10: 0000000000000008 R11: 0000000000000246 16351: 2025-09-02 14:05:53 <27739> R12: 00007fffa4739ae0 R13: 0000000000001000 16352: 2025-09-02 14:05:53 <27739> R14: 0000000000000010 R15: 00007f55d390c000 16353: 2025-09-02 14:05:53 <27739> RSI: 00007fffa4739870 RDI: 0000000000000002 16354: 2025-09-02 14:05:53 <27739> RBP: 00007fffa4739bc0 RSP: 00007fffa4739870 16355: 2025-09-02 14:05:53 <27739> RIP: 00007f55d8a3ce41 EFLAGS: 0000000000000246 16356: 2025-09-02 14:05:53 <27739> CS: 0033 FS: 0000 GS: 0000 16357: 2025-09-02 14:05:53 <27739> Trap: 0000000000000000 Error: 0000000000000000 16358: 2025-09-02 14:05:53 <27739> OldMask: 0000000000000000 16359: 2025-09-02 14:05:53 <27739> CR2: 0000000000000000 16360: 2025-09-02 14:05:53 <27739> stack: 0x7fffa4739870 - 0x7fffa473ab80 16361: 2025-09-02 14:05:53 <27739> Backtrace: 16362: 2025-09-02 14:05:53 <27739> [0x7f55d8a3ce41] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16363: 2025-09-02 14:05:53 <27739> [0x7f55d8a26557] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16364: 2025-09-02 14:05:53 <27739> [0x7f55d8a7e370] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16365: 2025-09-02 14:05:53 <27739> [0x7f55d8a8572a] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16366: 2025-09-02 14:05:53 <27739> [0x7f55d8a88a14] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16367: 2025-09-02 14:05:53 <27739> [0x7f55d8a8abb1] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16368: 2025-09-02 14:05:53 <27739> [0x7f55daef8551] => /bin/vwl {0x7f55d939e000} => vwl_service_optimize_member_reorder at ././daemon/vwl/vwl_service.c:2397 16369: 2025-09-02 14:05:53 <27739> [0x7f55daef8b5f] => /bin/vwl {0x7f55d939e000} => vwl_service_member_reorder_need at ././daemon/vwl/vwl_service.c:2643 16370: 2025-09-02 14:05:53 <27739> [0x7f55daef9733] => /bin/vwl {0x7f55d939e000} => vwl_service_do_install at ././daemon/vwl/vwl_service.c:2840 16371: 2025-09-02 14:05:53 <27739> [0x7f55daef9b73] => /bin/vwl {0x7f55d939e000} => vwl_service_install at ././daemon/vwl/vwl_service.c:2866 16372: 2025-09-02 14:05:53 <27739> [0x7f55dadf3612] => /bin/vwl {0x7f55d939e000} => check_expiration at ././migbase/sysapi/timer/timer.c:206 16373: 2025-09-02 14:05:53 <27739> [0x7f55dadf1c18] => /bin/vwl {0x7f55d939e000} => _fg_avl_traverse at ././migbase/sysapi/timer/fg_avl_tree.c:46 16374: 2025-09-02 14:05:53 <27739> [0x7f55daeec346] => /bin/vwl {0x7f55d939e000} => vwl_main at ././daemon/vwl/vwl_main.c:84 16375: 2025-09-02 14:05:53 <27739> [0x7f55d96fa952] => /bin/vwl {0x7f55d939e000} => fortiexecve at ././sysinit/fortiexec.c:878 16376: 2025-09-02 14:05:53 <27739> [0x7f55d97005fb] => /bin/vwl {0x7f55d939e000} => run_initentry at ././sysinit/init.c:1000 16377: 2025-09-02 14:05:53 <27739> [0x7f55d9700da6] => /bin/vwl {0x7f55d939e000} => run_initlevel at ././sysinit/init.c:1187 16378: 2025-09-02 14:05:53 <27739> [0x7f55d97037ae] => /bin/vwl {0x7f55d939e000} => initd_mainloop at ././sysinit/init.c:2554 16379: 2025-09-02 14:05:53 <27739> [0x7f55d970433b] => /bin/vwl {0x7f55d939e000} => main at ././sysinit/init.c:3038 16380: 2025-09-02 14:05:53 <27739> [0x7f55d8a27e1b] => /lib/libc.so.6 {0x7f55d8a04000} => ?? ??:0 16381: 2025-09-02 14:05:53 <27739> [0x7f55d96f5d2a] => /bin/vwl {0x7f55d939e000} => _start at /build/glibc/glibc-2.30/csu/../sysdeps/x86_64/start.S:122 16382: 2025-09-02 14:05:53 <27739> fortidev 6.0.2.0008 16383: 2025-09-02 14:05:53 the killed daemon is /bin/vwl: status=0x6 VWL is the Virtual WAN Link daemon related to SD-WAN features. There may be several reasons causing the crash. Things to take notes : How often does the crash happen: it could be a one-time event, and can be ignored if no service impact. If it frequently happens, then further investigation may be done. Any recent change to the SD-WAN setting. Compare the timestamp of the config change and the crashed time. Any recent firmware upgrade/downgrade. The crash could happen on some versions only. Open a Technical Support ticket to investigate further.