My apologies, the -fslgrad flag should not be there - I am getting the error without it. It seems the issue comes from b0_pair_XXX.mif not having a dw_scheme. This b0 image was created with dwiextract.
OK, I guess that’s kind of a result… It looks like there’s an issue running eddy, as the first error occurs when trying to format the error message produced by failing to run the OpenMP version of eddy (which is the fallback if the CUDA version fails). For some reason, trying to run the non-CUDA version produces an error message with non-ASCII characters, which that version of Python can’t convert to UTF-8. Seems OK with Python 3, though I don’t see any error message in your post – just the command invocation that failed. Any chance you could provide the full output of that failed command? And possibly any relevant information in the log files that you’ll find in the temporary folder the command would have created?
Thank you very much for your help! It seems that there was an issue with my XQuartz installation. Upon reinstalling it, everything seems to be running smoothly with the DW encoding information stripped as suggested in the other thread.