[Plugin: Latex Everything] Error on localhost while saving the post

The Latex Everything plugin is dependant on a program called pdflatex being installed on the computer WordPress is being run on. You can check whether you do have pdflatex by running the command which pdflatex in a terminal. If pdflatex is installed, it’ll echo something like /usr/texbin/pdflatex. If pdflatex isn’t installed, it won’t return anything.

You can get pdflatex at https://www.latex-project.org/ftp.html. You should also check you have the plugin’s other dependancy, pdftk: https://www.pdflabs.com/docs/install-pdftk/.