Wrong connection file argument (expecting a string

[simonhallstroem]

I installed two Maxima kernels (using CCL and SBCL) in jupyterhub (running inside a docker container). While the SBCL version starts, the CCL kernel doesn't and the command line output is

Maxima encountered a Lisp error:
Wrong connection file argument (expecting a string)

I am rather new to jupyterhub and therefore don't know what kind of additional information (config files, ...) I should provide here to make an analysis possible.

Any ideas would be appreciated.