# The fontspec package requires either XeTeX or LuaTeX to function [closed]

I am not an expert in LaTeX, but I was writing a paper, everything was going fine, until it suddenly crashed giving me the error:

The fontspec package requires either XeTeX or LuaTeX to function.

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That means that you have to use xelatex <document> or lualatex <document> instead of pdflatex <document> to compile your document if you want to use the fontspec package. For some background, try tex.stackexchange.com/q/36/86 –  Andrew Stacey Oct 4 '12 at 8:49
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This can't have happened suddenly. Either you changed how you compile your document (now using pdflatex instead of xelatex for example) or you added fontspec explicitly or a package that loads fontspec implicitly. –  cgnieder Oct 4 '12 at 11:07
As the error message said, LuaLaTeX or XeLaTeX should be used. Probably it wasn't the case. Since no further information was given, the question will now be closed as too localized. –  Stefan Kottwitz Oct 18 '12 at 12:20
@Stefan I tried compile a document with XeLaTeX and got this warning. –  Tyson Williams Aug 8 '13 at 20:26