“Alignment error” / “No alignment. Scan again, closer to previous scans.” 

Ensure nobody is at the side of the camera

Scan again closer to previous scan

Check doors and objects have not been moved

Mark windows and mirrors

If none of the above resolve the issue

Clean the mirror and the lens covering the LiDAR unit

Link to Matterport Error Messages Page

Zeiss Lens Wipes

Personal favourite for cleaning lenses of all kinds