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When I try to refer to a theorem in a section title with thref, I get the error message at the end of this question. Is there a way to fix this?

Latex Error: ./seppathq.tex:57 Argument of \@xtrplargoom has an extra }.

Runaway argument?
{\M@sect {subsection}{2}{\subsecindent }{\beforesubsecskip }{\aftersubsecskip \
Latex Error: ./seppathq.tex:57 Paragraph ended before \@xtrplargoom was complete.
Latex Error: ./seppathq.tex:57 Undefined control sequence.
Latex Error: ./seppathq.tex:57 Missing \endcsname inserted.

Runaway argument?

{{\M@sect {subsection}{2}{\subsecindent }{\beforesubsecskip }{\aftersubsecskip 
Latex Error: ./seppathq.tex:218 TeX capacity exceeded, sorry [main memory size=3000000].
Latex Error: ./seppathq.tex:218 ==> Fatal error occurred, no output PDF file produced!
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use \protect\ref – David Carlisle Sep 17 '12 at 18:43
@DavidCarlisle When I use \ref instead of \thref it works, however, I would like to use thref. When I use protect infront of \thref, I get: Missing \endcsname inserted. – sxd Sep 17 '12 at 19:29
Welcome to TeX.SX! A minimal example of code is needed. – egreg Sep 17 '12 at 19:51
@egreg, it is just simply \subsection{Proof of \thref{somereference}.} – sxd Sep 17 '12 at 20:05
up vote 5 down vote accepted

The following works:


\subsection{Proof of \protect\thref{test}}

Remove the .aux file before retrying: the preceding run without \protect has surely corrupted it.

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