Undefined value for option `gpu architecture`

You might get an error like this:

nvcc fatal   : Value 'sm_50' is not defined for option 'gpu-architecture'

This means most likely that the version of CUDA you are using is too old to support your GPU. The idiomatic fix for this is to upgrade CUDA, of course, but when you can't (like on a system not under your direct control) or you don't want to (because it is unreasonably hard), you can try specifying an older, hopefully compatible version by adding -arch=sm_35 to the nvcc.flags setting for Theano.

This could look like this, for example:

THEANO_FLAGS=device=gpu,floatX=float32,nvcc.flags=-arch=sm_35