invalid device function cudaGetLastError() on cuda-convnet dropout

When installing the library from this library :

https://github.com/dnouri/cuda-convnet

I came across this error :

invalid device function cudaGetLastError()

 All I had to do was to comment this line in the CMakeLists.txt file

#list(APPEND CUDA_NVCC_FLAGS -gencode arch=compute_30,code=sm_30)

and uncomment this line

 list(APPEND CUDA_NVCC_FLAGS -gencode arch=compute_20,code=sm_20)


The problem as described by this post

https://forums.udacity.com/questions/100015837/invalid-device-function-cudagetlasterror#cs344

is that the the device requirement is higher than what it is specified