ok. I have no idea what action_size is supposed to be, but



 dani_kal:

self.fc2 = nn.Linear(fc1_units + action_size[0], fc2_units)


will definitely work (as in, it will no longer give you this error)



 dani_kal:

TypeError: unsupported operand type(s) for +: ‘int’ and 'list’


As for this error message:



 dani_kal:

RuntimeError: CUDA error (35): CUDA driver version is insufficient for CUDA runtime version


I am not quite sure. It could be multiply things. The only thing I could say from the top of my head is:
Are you maybe loading a model like so model = torch.load(pathname)?
If so, you might wanna try and include a map_location like so: model = torch.load(pathname, map_location=map_location)
For CPU (your case I am assuming) that would be:
model = torch.load(pathname, map_location='cpu')