I have a simple .stan program for multilevel model that was running fine in Windows. But I was getting this strange error in Linux when I was running it.
'prep_call_sampler not found'
I tried to find the source of the problem, updated packages and looked up online for solutions. Finally, I saw a blog with a post describing a similar problem in the STAN forum
The solution was to simply replace the a*b with a * b in the .stan program and the model works fine in linux. Just thought of sharing this in case others face a similar problem when running stan program in linux using R.