If paths in afpd.conf are surrounded by quotation marks, the shares are ignored and the error "realpath() cannot resolve path" is logged.
To reproduce, put quotation marks around a pathname in afpd.conf and restart netatalk services.
Quotation marks around pathnames were allowed and handled correctly with prior versions of netatalk, as recently as 3.0.1.
Some thoughts – although afpd.conf is clearly parsed so that spaces in paths are included correctly, a fastidious administrator may prefer to put quotation marks around paths in order to ensure that, for example, "/tank/Backups/Time Machine" will not truncated and interpreted as "/tank/Backups/Time". It would therefore be worthwhile to handle quotation marks in a afpd.conf gracefully.