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I was previously able to run LaTeX with TeX Live 2011, but since installing TeX Live 2012, I get the error message ! I can't write on file 'texsys.aux'.

This is a Windows 7 operating system. I have tried processing a minimal working example from the command line using:

latex test.tex


This is some text.

The log file shows the following:

This is pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012/W32TeX) (INITEX)  4 JUN 2013 17:34
entering extended mode
restricted \write18 enabled.
%&-line parsing enabled.
! I can't write on file `texsys.aux'.
l.140 \immediate\openout15=texsys.aux

(Press Enter to retry, or Control-Z to exit; default file extension is `.tex')
Please type another output file name: 
! Emergency stop.
l.140 \immediate\openout15=texsys.aux
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That's odd: it is not processing the file that you showed but rather the source of latex itself, in intex mode. I can't guess why. What happens if you use pdflatex sample2e as the command, do you get a sample2e.pdf ? – David Carlisle Jun 4 '13 at 20:46
Thank you for your comment. I followed your suggestion and got the same error. – Martin Clouthier Jun 4 '13 at 20:59
I think the install failed and latex format was not made at install time (perhaps you didn't have write access to the directory) so every time you try to latex any file it is trying to make a latex format first and failing. – David Carlisle Jun 4 '13 at 21:05
That figures: It is failing to make each format latex, pdflatex, luaatex etc. If it can't write it is an operating system level restriction not a tex one. Do you have admin rights (if installing for all users) or installing it in your area (if installing it under a normal account). I don't use the windows install so I can't be specific... – David Carlisle Jun 4 '13 at 22:41
In any case, latex may say this also if given --output-dir, but that directory does not exist. – Ioannis Filippidis Jan 14 at 20:16

Ensure that you have full administrative privileges. In this case, my user ID belonged to the administrator group, but since the installation was taking place while the computer was not connected to the network (i.e., out of the office), administrator status could not be verified and privileges were restricted. IT staff was able to remotely login and run the installation successfully.

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