Troubleshooting Tip: Debug flow indicates an offloading-check failure with reason_code=1 for IPSec Traffic.

[acvaldez]

Description	This article  discusses the IPSec Tunnel Debug Flow error 'offloading-check failure with reason_code=1.'
Scope	FortiGate.
Solution	If a ping or any traffic to pass through the IPSec VPN tunnel is initiated, the following log entry in the debug flow for IPSec Tunnel traffic: 'offloading-check failed, reason_code=1' is observed. This error occurs when NPU Offloading on the IPSec tunnel configuration has been disabled. ------------------------------------ 2023-08-23 17:28:51 id=65308 trace_id=262 func=nipsec_set_ipsec_sa_enc line=965 msg="IPSec encrypt SA (p1/p2/spi={DCI1-KVDC-TH1/KVDC-LO10-TH1/0xd06d1331}) offloading-check failed, reason_code=1." ------------------------------------ Sample configuration: config vpn ipsec phase1-interface     edit tunnel_name         set npu-offload disabled     **** By default, this is enabled. ****     end