I (and unfortunately my client) keep having issues with warnings during the use of this plugin. Although this is (almost) entirely my own fault, I hope there might be a way to make the whole thing a bit more user friendly.
To use wp-mpdf correctly one has to set writing-permissions to certain folders. According to the installation instructions: wp-mpdf/cache AND wp-mpdf/tmp.
Another warning informed me that wp-mpdf/mpdf/graph_cache should also have writing-permissions. This is not in the installation instructions.
After updating the plugin this has to be done again. Which is where I go wrong, as I tend to forget there should be done some manual steps after hitting the update button...
Would it be possible for the plugin to use a standard wordpress folder like 'uploads' to handle its writing stuff? Or instruct the user to create a folder inside its theme folder for wp-mpdf to use? This way updates to the plugin will not destroy the folder permissions, and the plugin will keep on working.
Just a thought, and thanks for your great work on this plugin.