Warning everytime I start ICP Odometry and SLAM

[dinossht]

Anyone know why I get this warning everytime I start rtabmap with ICP odometry and SLAM.

[matlabbe]

It seems a local occupancy grid is missing, thus re-generated. If you are using the default config and it is not an old database, that could happen when an local occupancy grid failed to be created (invalid scan for example) in the first place.