Troubleshooting Tip: Security Fabric could not established after upgrading FortiGate VM-Azure to v7.4.8

After upgrading FortiGate-VM Azure to v7.4.8 security fabric could not be established in the Security Fabric tree, and members of the fabric cannot be seen because the csfd process keeps crashing.

diagnose debug crashlog read
6349: 2025-06-24 15:40:28 <26154> firmware FortiGate-VM64-AZURE v7.4.8,build2795b2795,250523 (GA.M)
16350: 2025-06-24 15:40:28 (Release)
16351: 2025-06-24 15:40:28 <26154> application csfd-unpriv
16352: 2025-06-24 15:40:28 <26154> *** signal 31 (Bad system call) received ***
16353: 2025-06-24 15:40:28 <26154> Register dump:
16354: 2025-06-24 15:40:28 <26154> RAX: 0000000000000060 RBX: 00007ffe5b550f30
16355: 2025-06-24 15:40:28 <26154> RCX: 00007ffe5b58ad79 RDX: 0000000017809bd7
16356: 2025-06-24 15:40:28 <26154> R08: 000055c901b1e480 R09: 0000000000000000
16357: 2025-06-24 15:40:28 <26154> R10: fffffffffffff4ed R11: 0000000000000246
16358: 2025-06-24 15:40:28 <26154> R12: 0000000000000000 R13: 00007ffe5b587080
16359: 2025-06-24 15:40:28 <26154> R14: 00007ffe5b550ef4 R15: 0017809bd76914f7
16360: 2025-06-24 15:40:28 <26154> RSI: 0000000000000000 RDI: 00007ffe5b550f30
16361: 2025-06-24 15:40:28 <26154> RBP: 00007ffe5b550f20 RSP: 00007ffe5b550ef0
16362: 2025-06-24 15:40:28 <26154> RIP: 00007ffe5b58ad79 EFLAGS: 0000000000000246
16363: 2025-06-24 15:40:28 <26154> CS: 0033 FS: 0000 GS: 0000
16364: 2025-06-24 15:40:28 <26154> Trap: 0000000000000000 Error: 0000000000000000
16365: 2025-06-24 15:40:28 <26154> OldMask: 0000000000000000
16366: 2025-06-24 15:40:28 <26154> CR2: 0000000000000000
16367: 2025-06-24 15:40:28 <26154> Backtrace:
16368: 2025-06-24 15:40:28 <26154> [0x7f6ac0f05003] => /lib/libc.so.6 {0x7f6ac0e3e000}
16369: 2025-06-24 15:40:28 <26154> [0x7f6ac0f04f3a] => /lib/libc.so.6 {0x7f6ac0e3e000}
16370: 2025-06-24 15:40:28 <26154> [0x55c8f3378a3e] => /bin/csfd {0x55c8f2b97000}
16371: 2025-06-24 15:40:28 <26154> [0x7f6ac0e76ec0] => /lib/libc.so.6 {0x7f6ac0e3e000}
16372: 2025-06-24 15:40:28 <26154> [0x7ffe5b58ad79] => [vdso] {0x7ffe5b58a000}
16373: 2025-06-24 15:40:28 <26154> [0x7f6ac07ac9ce] => /lib/libssl.so.3 {0x7f6ac0783000}

16374: 2025-06-24 15:40:28 <26154> [0x7f6ac07cff01] => /lib/libssl.so.3 {0x7f6ac0783000}
16375: 2025-06-24 15:40:28 <26154> [0x7f6ac07d0292] => /lib/libssl.so.3 {0x7f6ac0783000}
16376: 2025-06-24 15:40:28 <26154> [0x7f6ac0846144] => /lib/libssl.so.3 {0x7f6ac0783000}
16377: 2025-06-24 15:40:28 <26154> [0x7f6ac083262b] => /lib/libssl.so.3 {0x7f6ac0783000}
16378: 2025-06-24 15:40:28 <26154> [0x55c8f33a9ecf] => /bin/csfd {0x55c8f2b97000}
16379: 2025-06-24 15:40:28 <26154> [0x55c8f5a0c246] => /bin/csfd {0x55c8f2b97000}
16380: 2025-06-24 15:40:28 <26154> [0x55c8f3386a8b] => /bin/csfd {0x55c8f2b97000}
16381: 2025-06-24 15:40:28 <26154> [0x55c8f2e8b413] => /bin/csfd {0x55c8f2b97000}
16382: 2025-06-24 15:40:28 <26154> [0x7f6ac0e61e1b] => /lib/libc.so.6 {0x7f6ac0e3e000}
16383: 2025-06-24 15:40:28 <26154> [0x55c8f2e8629a] => /bin/csfd {0x55c8f2b97000}
16384: 2025-06-24 15:40:28 <26154> fortidev 6.0.2.0008
Crash log interval is 3600 seconds
csfd-unpriv crashed 42 times.

In the above example, the process was crashed 42 times. The issue is resolved in v 7.4.9 (it will be available by the end of the second week of September) and v7.6.3 (currently available).

Note: This issue is also observed on FortiGate 120G/121G models.

Related article: 

Technical Tip: Security Fabric Connection Failure on FortiGate Azure VM and FortiGate 120G/121G After Firmware Upgrade