[ERROR] Index doesn't exists in the specified directory.

Recently noticed this message in the activity log, which unfortunately dates back to November 2016, probably during an upgrade from 7.2.2. Previewing, opening and importing downloaded email takes 1-2 minutes each, all other SuiteCRM activities are satisfactory.

Saw the suggestion at https://github.com/salesagility/SuiteCRM/issues/1007
Recommends to create the following empty files in modules/AOD_Index/Index/Index/

Created the following files (with the exception of (read.lock.file that already existed):

-rw-rw-rw- 1 www-data www-data 0 Feb 27 03:00 optimization.lock.file
-rw-rw-rw- 1 www-data www-data 0 Feb 27 15:01 read.lock.file
-rw-rw-rw- 1 www-data www-data 0 Feb 27 03:00 read-lock-processing.lock.file
-rw-rw-rw- 1 root root 43 Feb 27 03:00 segments_1uc
-rwxrwxr-x 1 www-data www-data 20 Feb 27 03:00 segments.gen*
-rw-rw-rw- 1 www-data www-data 0 Feb 27 03:00 write.lock.file

This did not resolve the error message. It’s possible that there is another /index/(contents) that is needed after the upgrade but without a reference point I think it would be dangerous to create them.