Error in export a DetectNet_v2 model in INT8 mode

Firstly, please check below requirements of TLT according to Integrating TAO Models into DeepStream — TAO Toolkit 3.22.05 documentation

Hardware Requirements

Minimum

4 GB system RAM
4 GB of GPU RAM
Single core CPU
1 GPU
50 GB of HDD space

Recommended

32 GB system RAM
32 GB of GPU RAM
8 core CPU
4 GPUs
100 GB of SSD space

Software Requirements
Ubuntu 18.04 LTS
NVIDIA GPU Cloud account and API key - https://ngc.nvidia.com/
docker-ce installed, Install Docker Engine on Ubuntu | Docker Documentation
nvidia-docker2 installed, instructions: Installation (version 2.0) · NVIDIA/nvidia-docker Wiki · GitHub
NVIDIA GPU driver v410.xx or above
Note: DeepStream 4.0 - NVIDIA SDK for IVA inference https://developer.nvidia.com/deepstream-sdk is recommended.