I use the BlueField-3 card as the NVMe-oF Target, and the networking is as follows:
[X86/Initiator]----- NVMe-oF(RDMA)-------[BlueField/Target] — NVME-SSD

What could be the cause of this error?

mlx5_fw: 0000:03:00.0 [0x2d20d6e56ec4] 0 [0x5] handle_nvmf_respond_exception sending_uapp_sw_cqe: gvmi: 0x0,qpn: 0x129

mlx5_fw: 0000:03:00.0 [0x2d20d6e5898c] 0 [0x5] handle_ace_req_cqe_error release: gvmi 0x0, tgt_num 0x10, qpn 0x129, action: 0x80000004

Thanks in advance for any assistance or suggestions.

BlueField-3 SmartNIC Main Card (900-9D3C6-00SV-DA0)
Linux 5.15.0-1032-bluefield

Further analysis would be needed to specifically root cause this error.
I would suggest opening a support case should you have a support contract entitlement for your BF3.
We will further analyze and debug.
Enterprise Support EnterpriseSupport@nvidia.com