command line package manager mpm --update prints Invalid argument: Data: biblatex

Dear miktex-users,

On the command line in Windows 7 64bit, mpm --update gives the following 
output:

(The precise version follows below. This problem persists for other 
repositories and if cmd.exe is started with administrator privileges.)

==

C:\Users\Enno>mpm --verbose --update
downloading 
ftp://distrib-coffee.ipsl.jussieu.fr/pub/mirrors/ctan/systems/win32/miktex/tm/packages/miktex-zzdb2-2.9.tar.lzma...
739927 bytes, 453.32 KB/Sec
updating package definition directory 
(C:\Users\Enno\AppData\Roaming\MiKTeX\2.9\tpm\packages)...
installed 2428 package definition files
visiting repository 
ftp://distrib-coffee.ipsl.jussieu.fr/pub/mirrors/ctan/systems/win32/miktex/tm/packages/...
repository type: remote package repository
loading lightweight database...
downloading 
ftp://distrib-coffee.ipsl.jussieu.fr/pub/mirrors/ctan/systems/win32/miktex/tm/packages/miktex-zzdb1-2.9.tar.lzma...
143927 bytes, 375.81 KB/Sec
lightweight database digest: 8a9d030e8c8fa3aaa59a4f1bbb445ea5
starting package maintenance...
installation directory: C:\Users\Enno\AppData\Roaming\MiKTeX\2.9
package repository: 
ftp://distrib-coffee.ipsl.jussieu.fr/pub/mirrors/ctan/systems/win32/miktex/tm/packages/
lightweight database digest: 8a9d030e8c8fa3aaa59a4f1bbb445ea5
going to download 7853713 bytes
going to install 234 file(s) (2 package(s))
downloading 
ftp://distrib-coffee.ipsl.jussieu.fr/pub/mirrors/ctan/systems/win32/miktex/tm/packages/biblatex.tar.lzma...
6855642 bytes, 818.36 KB/Sec
mpm: Invalid argument.
mpm: Data: biblatex

==

C:\Users\Enno>mpm --version
MiKTeX Package Manager 2.9.4620 (MiKTeX 2.9 64-bit)
Copyright (C) 2005-2011 Christian Schenk
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

==

Sincerely yours

   Enno

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