[tex-live] Error: Unknown format directive

[Arno Trautmann]

Hi all,

I just wanted to install TeX Live 2015 to a windows 7 machine. Package 
downloading succeeded, mktexlsr ran fine, but then I run into the 
following error and the intallation is not finished:

--
writing fmtutil.cnf to C:/texlive/2015/texmf-dist/web2c/fmtutil.cnf
Tk::Error: Unknown format directive 
fmttriggers=cm,hyphen-base,knuth-lib,plain,package aleph, execute 
AddFormat name=aleph engine=aleph options=*aleph.ini
       fmttriggers=cm,hyphen-base,knuth-lib,plain at 
C:/Users/matterwave/Desktop/install-tl-20150819/tlpkg/TeXLive/TLPOBJ.pm 
line 981.
  TeXLive::TLPOBJ::fmtutil_cnf_lines at 
C:/Users/matterwave/Desktop/install-tl-20150819/tlpkg/TeXLive/TLPOBJ.pm 
line 981
  TeXLive::TLPDB::fmtutil_cnf_lines at 
C:/Users/matterwave/Desktop/install-tl-20150819/tlpkg/TeXLive/TLPDB.pm 
line 2152
  TeXLive::TLUtils::create_fmtutil at 
C:/Users/matterwave/Desktop/install-tl-20150819/tlpkg/TeXLive/TLUtils.pm 
line 2821
  main::do_postinst_stuff at 
C:\Users\matterwave\Desktop\install-tl-20150819\install-tl line 924
  main::do_installation at 
C:\Users\matterwave\Desktop\install-tl-20150819\install-tl line 790
  main::wizard_installation_window at 
C:/Users/matterwave/Desktop/install-tl-20150819/tlpkg/installer/install-menu-wizard.pl 
line 709
  Tk callback for .button2
  Tk::__ANON__ at 
C:\Users\matterwave\Desktop\install-tl-20150819\tlpkg\tlperl\lib/Tk.pm 
line 251
  Tk::Button::butUp at 
C:\Users\matterwave\Desktop\install-tl-20150819\tlpkg\tlperl\lib/Tk/Button.pm 
line 175
  <ButtonRelease-1>
  (command bound to event)
--

Online search for the given error just returns the TLUtils.pm script.
The same problem happened to a colleague of mine, so it seems not to be 
a problem of my machine. We are behind a proxy, which should be 
configured fine since the package loading worked. If I can give any 
other information so you could point me at a solution, I'll happily 
provide them.

Any help is highly appreciated,
best,

Arno