Hi @eeee -
First, I should point out that the WHS template is a rat template, not a mouse template, and I’ve found that the size difference is too large for registration algorithms to overcome.
Unfortunately, mouse data is not yet supported for fMRIPrep-rodents, as I mentioned in the message above.
Your error indicates that the pipeline is struggling to find the WHS brain mask from templateflow. It is difficult to help more without knowing how you are running fMRIPrep-rodents. Do you have access to the directory that the pipeline is looking in?