The system libraries have changed on newer versions of Linux such that the freesurfer 6 binaries can no longer read the license file. Freesurfer 6 was released in 2017 at the time when CentOS6 (RedHat 6) and MacOS 10.7 were still relatively current. Some 8 years later, the encryption, etc., libraries have changed on current Linux OS’s. Also, qdec has been deprecated (no longer supported) in the subsequent 7.X and 8.X freesurfer releases where the alternative is to use freeview and commands like mris_surf2surf mri_glmfit, mri_glmfit-sim, etc., for stream processing. Any license you download now should work with the 7.X and 8.X releases.

If you already have experience using a version of a Linux OS where you were able to run the 6.0 release using your own personal or perhaps your institutions license file, then I would try and duplicate that setup. That may mean you need to use a container or VM to host that older version of the Linux OS where FS6 could read the license file on top of a newer version of Linux OS, i.e., if the original system where FS6 ran is no longer available.

- R.

On Nov 15, 2025, at 21:02, Henry Do <minhhiep.do@sydney.edu.au> wrote:

External Email - Use Caution
Hi Freesurfer expert,

I am having an error with the QDEC. I am using Freesurfer v6.0 stable and it keeps giving me error when I do the analyze.. I can load the qdec table and all other commands still run fine but when I did the analyze, it gave this error. I have converted the license.txt to $FREESURFER_HOME/.license like previous suggestion but doesn't work.

Writing to /home/henrydo/subjects/qdec/Untitled/contrasts.sig.mgh
--------------------------------------------------------------------------
ERROR: Invalid FreeSurfer license key found in license file /home/henrydo/software/freesurfer/.license
If you are outside the NMR-Martinos Center,
go to http://surfer.nmr.mgh.harvard.edu to
get a valid license file (it's free).
If you are inside the NMR-Martinos Center,
make sure to source the standard environment.
--------------------------------------------------------------------------

I want to use QDEC to see which subjects will have impacts on different regions. If possible, I would like to have instruction how to do visualize it without qdec.

Many thanks,
Henry
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