Same problem since upgrading from El Capitan to Sierra 10.12.4. Meshlab runs from the DMG as normal, but dragging to Applications causes an error. Now, the main change I made to my OS on upgrading to Sierra was that i formatted my hard disk CASE SENSITIVE. This has broken a few apps and it might have damaged something in Meshlab's plist file. Hopefully it's just a case sensitivity problem in which case it should be an easy fix once we can figure out what...