Dear Joshua,

we had the same problem with freeSurfer 5.3.0 on Debian GNU/Linux 8.3 (jessie). In our case this was warning, the qdec launched, however the fsgd plot functionality (interactive vertex-wise GLM plot display) did not work.

It seems that the error is caused by interference of tk/blt libraries packaged with freeSurfer with those installed on the system.

We were able to resolve this issue by uninstalling following installed packages:

tk8.6-blt2.5 blt

If this do not help to you, try to run

strace -f qdec

and inspect, which libraries are loaded during initialization on your system before the error is issued.

Regards,

Antonin Skoch