Some problems can be fixed by downloading a fresh copy of TileMill and installing again. Open the Terminal and enter the following command to do so.
sudo apt-get install tilemill
This will reset any customizations you have made to TileMill preferences and will remove any TileMill plugins you have installed.
Open the Terminal, type
cd ~/.tilemill, and press enter.
config.json file and the
node_modules folder by entering the following commands:
mv config.json config.json.backup mv node_modules node_modules.backup
Documentsdirectory in the file manager.
MapBox-backupto backup your projects.
MapBoxdirectory should be created. If the application now behaves properly, copy the
MapBox-backupto the newly created
MapBoxfolder to restore your projects.
TileMill depends on a custom Mapnik build that sits beside TileMill in its Ubuntu PPA. If you have any other version of Mapnik installed this will prevent TileMill from working properly (unless you have built TileMill from source).
See the version of Mapnik you have installed by doing:
apt-cache policy libmapnik
The installed version should match the name of the Mapnik package at the TileMill PPA.