Troubleshooting Tip: The sslvpnd daemon crashed, causing the SSL VPN connection to drop after enabling dual-stack-mode in the SSL VPN settings

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Description	This article describes how to handle a situation where the sslvpnd daemon with FortiGate firmware v7.0.8 build0418 crashes. It causes the SSL VPN connection to drop after enabling dual-stack-mode feature in the SSL VPN settings.
Scope	FortiGate v7.0.8.
Solution	When configuring addrgrp6 in srcaddr6 settings under the firewall policy at FortiGate unit, and with the dual-stack-mode feature enabled in SSL VPN settings, the sslvpnd daemon will crash and the SSL VPN connection will come down. config firewall addrgrp6     edit "all_sslvpn_ipv6"         set member "sslvpn_users_ipv6" "sslvpn_users2_ipv6"     next end config firewall policy     edit <Policy ID>         set srcintf "port1"         set dstintf "port2"         set action accept         set srcaddr "all_sslvpn"         set dstaddr "10.154.0.1"         set srcaddr6 "all_sslvpn_ipv6"         set dstaddr6 "false_ipv6"         set schedule "always"         set service "ALL"         set groups "vpn_users_group"     next end config vpn ssl settings     set dual-stack-mode enable end Run the following CLI command to see the following logs: diagnose debug crashlog read 51367: 2025-07-15 15:24:45 <01504> firmware FortiGate-101F v7.0.8,build0418b0418,221012 (GA.F) (Release) 51368: 2025-07-15 15:24:45 <01504> application sslvpnd 51369: 2025-07-15 15:24:45 <01504> *** signal 11 (Segmentation fault) received *** 51370: 2025-07-15 15:24:45 <01504> Register dump: 51371: 2025-07-15 15:24:45 <01504> R0: 0000000004b0a3e8   R1: 0000000000000001   R2: 00000000043d4750 51372: 2025-07-15 15:24:45 <01504> R3: 000000000274b328   R4: 0000000000000000   R5: 00000000000000ca 51373: 2025-07-15 15:24:45 <01504> R6: 0000000000000180   R7: fefefeff736e6e71   XR: 7f7f7f7f7f7f7f7f 51374: 2025-07-15 15:24:45 <01504> R9: 0000000000000036   R10: 0101010101010101   R11: 0000000000000020 51375: 2025-07-15 15:24:45 <01504> R12: 0000000000000000   R13: 0000000000000000   R14: 0000000000000002 51376: 2025-07-15 15:24:45 <01504> R15: 0000000000000000   IP0: 00000000043d8a38   IP1: 0000007f85006740 51377: 2025-07-15 15:24:45 <01504> PR: 0000000000000000   R19: 00000000092f0ff0   R20: 00000000043d7000 51378: 2025-07-15 15:24:45 <01504> R21: 0000000000000065   R22: 00000000092f0ff0   R23: 0000000000000003 51379: 2025-07-15 15:24:45 <01504> R24: fffffffffffffec0   R25: 0000000000000000   R26: 0000007f837905dc 51380: 2025-07-15 15:24:45 <01504> R27: fffffffffffffec0   R28: 000000001bf9d120   FP: 0000007fd8579120 51381: 2025-07-15 15:24:45 <01504> fault_address: 0000007fd8578fe0   sp: 0000007fd8579120 51382: 2025-07-15 15:24:45 <01504> pc: 000000000274b328   lr: 00000000020b428c 51383: 2025-07-15 15:24:45 pstate: 80000000 (Nzcv daif -PAN -UAO) 51384: 2025-07-15 15:24:45 backtrace too deep 51385: 2025-07-15 15:24:45 <01504> Backtrace: 51386: 2025-07-15 15:24:45 <01504> [0x0274b328] => /bin/sslvpnd  51387: 2025-07-15 15:24:45 <01504> [0x020b428c] => /bin/sslvpnd  51388: 2025-07-15 15:24:45 <01504> [0x020b468c] => /bin/sslvpnd  51389: 2025-07-15 15:24:45 <01504> [0x020b47fc] => /bin/sslvpnd  51390: 2025-07-15 15:24:45 <01504> [0x020b0100] => /bin/sslvpnd  51391: 2025-07-15 15:24:45 <01504> [0x020b03dc] => /bin/sslvpnd  51392: 2025-07-15 15:24:45 <01504> [0x020b22f0] => /bin/sslvpnd  51393: 2025-07-15 15:24:45 <01504> [0x020ab0e8] => /bin/sslvpnd  51394: 2025-07-15 15:24:45 <01504> [0x0204fdb8] => /bin/sslvpnd  51395: 2025-07-15 15:24:45 <01504> [0x0204dc10] => /bin/sslvpnd  51396: 2025-07-15 15:24:45 <01504> [0x0204e178] => /bin/sslvpnd  51397: 2025-07-15 15:24:45 <01504> [0x020b2698] => /bin/sslvpnd  51398: 2025-07-15 15:24:45 <01504> [0x020ab0e8] => /bin/sslvpnd  51399: 2025-07-15 15:24:45 <01504> [0x020bacd0] => /bin/sslvpnd  51400: 2025-07-15 15:24:45 <01504> [0x020bb234] => /bin/sslvpnd  51401: 2025-07-15 15:24:45 <01504> [0x020b265c] => /bin/sslvpnd  51402: 2025-07-15 15:24:45 <01504> [0x020ab0e8] => /bin/sslvpnd  51403: 2025-07-15 15:24:45 <01504> [0x016d3b2c] => /bin/sslvpnd  51404: 2025-07-15 15:24:45 <01504> [0x016d3b6c] => /bin/sslvpnd  51405: 2025-07-15 15:24:45 <01504> [0x016d3b6c] => /bin/sslvpnd  51406: 2025-07-15 15:24:45 <01504> [0x016d3b6c] => /bin/sslvpnd  51407: 2025-07-15 15:24:45 <01504> [0x016d3b6c] => /bin/sslvpnd  ... 51638: 2025-07-15 15:24:45 <01504> [0x016d3b6c] => /bin/sslvpnd  51639: 2023-02-16 15:26:12 <01504> fortidev 6.0.1.0005 To fix: For a workaround with a temporary fix: Disable the dual-stack-mode feature in SSL VPN settings. config vpn ssl settings     set dual-stack-mode disable end For a permanent fix: It is necessary to upgrade FortiGate firmware version to be v7.2.11, v7.4.0, and above.