Quicklook was not working (i.e. the visual icon preview for application files in the finder).
First I read man qlmanage and tried what is suggested there.
Following that, output from qlmanage -t ~/Documents/SKETCH/960.sketch is below.
High Sierra security feature breaking quicklook?
Testing Quick Look thumbnails with files:
/Users/m/Documents/SKETCH/960.sketch
2018-01-12 12:02:03.084 qlmanage[681:10248] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0x8f3b, name = 'com.apple.tsm.portname'
See /usr/include/servers/bootstrap_defs.h for the error codes.
dyld: warning, LC_RPATH @executable_path/../Frameworks in /Applications/Sketch.app/Contents/Library/QuickLook/SketchQuicklook.qlgenerator/Contents/MacOS/../../../../../Frameworks/BCFoundation.framework/Versions/A/BCFoundation being ignored in restricted program because of @executable_path
dyld: warning, LC_RPATH @executable_path/Frameworks in /Applications/Sketch.app/Contents/Library/QuickLook/SketchQuicklook.qlgenerator/Contents/MacOS/../../../../../Frameworks/BCFoundation.framework/Versions/A/BCFoundation being ignored in restricted program because of @executable_path
* /Users/m/Documents/SKETCH/960.sketch produced one thumbnail
Done producing thumbnails
2018-01-12 12:02:03.252 qlmanage[681:10248] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0x14f2f, name = 'com.apple.coredrag'
See /usr/include/servers/bootstrap_defs.h for the error codes.
