Compiling error after latest MiKTeX update (hyperref)

After the latest update (which included an update of the package 
hyperref) without any change to a (large) document I get a compiling error:


! LaTeX Error: Encoding scheme `PU' unknown.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
  ...

l.4058 \ProcessKeyvalOptions{Hyp}

What can I do to get the document compiled again as it worked some two 
days before?

Thanks in advance
Ralf


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