On Fri, 8 Jun 2012, Jörg Weber wrote:

> (This is an issue I originally posted here: http://tex.stackexchange.com/questions/58760/lualatex-fontspec-cannot-compare-documents-with-acrobat and I cross-posted on the LuaTeX User Mailing list)
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> I use the option "compare documents" in Adobe Acrobat Pro a lot to highlight changes between revisions. What I just noticed is, if I compile a simple document such as the one below with LuaLaTeX + fontspec, Acrobat is unable to perform the comparison, giving a unspecific error message ("cannot compare document..."). Compiling the same document without fontspec allows the comparison, as does XeLaTeX + fontspec.
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> I tried with TeX Live 2012 and the current MikTeX, without success. 
> Ulrike Fischer suggested \usepackage{luaotfload} \font\test=Arial 
> \pagestyle{empty} and \test after \begin{document} instead of fontspec, 
> but the error remains. Does anyone know what is going on and of a 
> possible fix?

Do you know what happens if you try with a simple ConTeXt document with 
opentype fonts?

\setupbodyfont[palatino]
\starttext
Hello world
\stoptext

Compile with "context filename"

Aditya