cudaFree

I have a question about the cuda function ‘cudaFree’
When I try to reproduce a program about SpMV, it shows error bellow:
'CUDA error at external/CSR5_cuda/detail/cuda/format_cuda.h:18 code=0(cudaSuccess) “cudaFree(d_scan)” ’
I run it on NVIDIA RTX 3090 Ti , Linux, CUDA 11.1
The program is bellow:

(My bolding)
This actually tells you that cudaFree succeeded and that there was no error.

Many thanks!