In last blog, we created a xml file that can be verified in mujoco simulator. But when i tested it in mujoco py and try to training it using HER of baseline, it showed one error, this error means every body must had at least one "site" which would be used in follow environment training stage. So the verified xml file was as shown in the following (under path of "~/gym/gym/envs/robotics/assets/fetch"): P.s. 'target0' was used to visualize the target during training stage in <!--load floor--> part!