This error is triggered when your (real or simulated) robot is unable to follow the planned trajectory precisely enough. There could be several different root causes of this.
A. The controllers on your robot may not be well tuned, so that the error between their set point and actual position becomes too great. If you've built your own robot in Gazebo this may be likely.
B. The path planner has produced a trajectory which the robot is physically incapable of following. If the speed or acceleration limits of the joints are set unrealistically high then the trajectory will be impossible for the robot to follow.
C. The path tolerance may be set unrealistically fine.
Things to try:
- Lower the speed and acceleration multipliers in the Moveit GUI (or API if you're using that)
- Try improving the tuning of your PID controllers if you made the robot yourself.
- Increase the path tolerance, but make sure your robot is still accurate enough to achieve its task and safely avoid collisions.
Also can describe your robot model in Gazebo, is it a ready made one or have you make it yourself?