As with others, I encountered issues compiling PDFs when I updated my OS to El Capitan. I followed the directions listed on the TexMaker website for changing /usr/texbin paths to /Library/Tex/texbin and it worked like a charm. Then, I upgraded my OS to High Sierra and TexMaker stopped compiling PDFs. Once again, I followed the directions listed on the TexMaker website and changed all of the /usr/texbin paths to /Library/Tex/texbin. Unfortunately, that did not work this time. I've triple-checked for typos in the paths and found none.
I also removed all documents except the .tex file from the folder and clicked on the "Quick Build" button to see what would happen. I received a "Could not start the command" error message.
Please help. Why is TexMaker suddenly failing to compile my PDFs?