Technical Tip: Frequent cw_acd Daemon Crashes Impact WiFi Service After Firmware Upgrade to v7.6.1

The cw_acd daemon crashes frequently after upgrading to v7.6.1, leading to WiFi service disruptions.

This issue occurs only when SNMP is enabled and SNMP polling is performed on the FortiGate while a wireless STA is connected to the Tunnel VAP. Crashlog may indicate that the CAPWAP AC daemon 'cw_acd' is crashing frequently.

diagnose debug crashlog read
8709: 2025-01-21 09:09:38 <13790> firmware FortiGate-121G v7.6.1,build3457b3457,241127 (GA.F) (Release)
8710: 2025-01-21 09:09:38 <13790> application cw_acd
8711: 2025-01-21 09:09:38 <13790> *** signal 11 (Segmentation fault) received ***
8712: 2025-01-21 09:09:38 <13790> Register dump:
8713: 2025-01-21 09:09:38 <13790> R0: 50525f5041435f41 R1: 00000055636246a0 R2: 000000000000ae28
8714: 2025-01-21 09:09:38 <13790> R3: 0000005589f47230 R4: 0000000000018718 R5: 0000000000000055
8715: 2025-01-21 09:09:38 <13790> R6: 0000000000000166 R7: 0000005563cc9000 XR: 00000000000000cf
8716: 2025-01-21 09:09:38 <13790> R9: 0000000000000010 R10: 000000000000125e R11: 00000000000a5e1d
8717: 2025-01-21 09:09:38 <13790> R12: 6b636f536c697455 R13: 00373630322e7465 R14: 0000000000000000
8718: 2025-01-21 09:09:38 <13790> R15: 000038e53dc08853 IP0: 00000055635d8c50 IP1: 0000007f97415580
8719: 2025-01-21 09:09:38 <13790> PR: 0000000000000009 R19: 0000005589b3b44a R20: 0000005563624660
8720: 2025-01-21 09:09:38 <13790> R21: 00000055635e4000 R22: 0000000000000000 R23: 00000055636246a0
8721: 2025-01-21 09:09:38 <13790> R24: 0000007ff9ac394c R25: 0000005589b3b44a R26: 0000000000000098
8722: 2025-01-21 09:09:38 <13790> R27: 0000000000000010 R28: 0000005589b3b33a FP: 0000007ff9ac38e0
8723: 2025-01-21 09:09:38 <13790> fault_address: 00525f5041436119 sp: 0000007ff9ac38c0
8724: 2025-01-21 09:09:38 <13790> pc: 000000555f097384 lr: 000000555f0aa1dc
8725: 2025-01-21 09:09:38 <13790> pstate: 20000000 (nzCv daif -PAN -UAO)
8726: 2025-01-21 09:09:38 <13790> Backtrace:
8727: 2025-01-21 09:09:38 <13790> [0x555f097384] => /bin/cw_acd {0x555ea36000}
8728: 2025-01-21 09:09:38 <13790> [0x555f0aa1dc] => /bin/cw_acd {0x555ea36000}
8729: 2025-01-21 09:09:38 <13790> [0x555f0f3b78] => /bin/cw_acd {0x555ea36000}
8730: 2025-01-21 09:09:38 <13790> [0x555f1deca8] => /bin/cw_acd {0x555ea36000}
8731: 2025-01-21 09:09:38 <13790> [0x555f120fe4] => /bin/cw_acd {0x555ea36000}
8732: 2025-01-21 09:09:38 <13790> [0x555ee264bc] => /bin/cw_acd {0x555ea36000}
8733: 2025-01-21 09:09:38 <13790> [0x555ee2c994] => /bin/cw_acd {0x555ea36000}
8734: 2025-01-21 09:09:38 <13790> [0x555ee2d1f0] => /bin/cw_acd {0x555ea36000}
8735: 2025-01-21 09:09:38 <13790> [0x555ee3008c] => /bin/cw_acd {0x555ea36000}
8736: 2025-01-21 09:09:38 <13790> [0x555ee30b80] => /bin/cw_acd {0x555ea36000}
8737: 2025-01-21 09:09:38 <13790> [0x7f973b7f24] => /lib/libc.so.6 {0x7f97397000}
8738: 2025-01-21 09:09:38 <13790> fortidev 6.0.2.0008
8739: 2025-01-21 09:09:38 the killed daemon is /bin/cw_acd: status=0x0
8740: 2025-01-21 09:14:48 cw_acd previously crashed 5 times. The last crash was at 2025-01-21 09:09:38.

This issue has been resolved in FortiOS versions 7.6.3 and 7.4.8.

Workaround:
Disable SNMP on FortiGate.