[Tex/LaTex] Error “Please insert PRERENDERUNICODE”

amsartinput-encodingsunicode

I meet a subtle problem. My simplest code is as follows. I am working in Win 7-32bit, my editor is WinEdt 7.0 (Build: 20120125 (v. 7.0)), saved as UTF-8, compiled with pdflatex(MiKTeX2.9).

\documentclass{amsart}
\usepackage[utf8x]{inputenc}

\begin{document}

\title{U}%Ü
\author{ü}
\date{\today}
\maketitle

\end{document}

The result is enter image description here, there is error message 

[PLEASEINSERT\PRERENDERUNICODE{}INTOPREAMBLE]

What subtle is if I change amsart to article, or change the first U to Ü, the problem disappears.

Best Answer

This is due to a slight incompatibility of utf8x with amsart (that capitalizes the author's name).

You have two paths to follow:

  1. say \usepackage[utf8]{inputenc}

  2. make the offending character known to ucs and utf8x before \begin{document}

Path 1 is preferable, if you don't use characters that aren't covered by this option (and even if you do, as it's usually easy to add the needed ones).

If you stick with utf8x, then say as it's said in quite a cryptic way in the output: add

\PrerenderUnicode{ü}

in the preamble (after loading \inputenc). Add all the accented characters that might offend ucs (that's automatically loaded).

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