I am converting myself to MkIV, and ran into the following error: ! LuaTeX error /usr/share/texmf/tex/context/base/meta-pdf.lua:355: attempt to call global 'pdfgrayliteral' (a nil value) stack traceback: /usr/share/texmf/tex/context/base/meta-pdf.lua:355: in function [C]: in function 'lpegmatch' /usr/share/texmf/tex/context/base/meta-pdf.lua:519: in function 'parse' /usr/share/texmf/tex/context/base/meta-pdf.lua:539: in function 'convertmpstopdf' <main ctx instance>:1: in main chunk. It was during converting metapost to pdf. The metapost source has: defaultcolormodel := 3; % grayscale which may be why this problem wasn't noticed before. But the patch below fixes it for me (after regenerating the format, which took me a while to realize): --- /usr/share/texmf/tex/context/base/meta-pdf.lua 2012-05-14 13:38:55.000000000 -0400 +++ /usr/share/texmf/tex/context/base/meta-pdf.lua 2013-04-11 14:54:45.000000000 -0400 @@ -352,7 +352,7 @@ function mps.setgray(s) pdfcode(pdffinishtransparencycode()) - pdfcode(pdfgrayliteral(mps.colormodel,s)) + pdfcode(pdfgraycode(mps.colormodel,s)) end function mps.specials(version,signal,factor) -- 2.0 123 1000