beamer doesn't work after upgrading to MiKTeX 2.9 – 20 error messages

Question

After upgrading to MiKTeX 2.9 my beamer files stopped working. The code:

\documentclass{beamer} 
\begin{document} 
\begin{frame} 
Hello 
\end{frame} 
\end{document}

Gives some 20 errors and two warnings, the first error being:

! Undefined control sequence.
<argument> ...eamer@linkspace {6pt}\Hy@xspace@end 
                             \Hy@LinkMath \Hy@SaveSpace...

and the first warning:

LaTeX Font Warning: Font shape `OT1/cmss/m/n' in size <4> not available
(Font)              size <5> substituted on input line 3.

The log file is available here.

I have searched the web in vain, for example tried deleting the .aux file as suggested at Beamer - undefined control sequence, the solutions did not work.

Answer 1

update the package hyperref. If it is not available with MiKTeX (for TeXLive it was updated yesterday) try in the preamble:

\makeatletter\def\Hy@xspace@end{}\makeatother