Error: mrconvert cannot import diffusion gradient table

Sorry, we had the ISMRM conference last week, and it was as intense as it always is.

To answer your question, it sounds like you need to familiarise yourself with the documentation, particularly image handling in MRtrix3, DW encoding handling, and DICOM handling. I also recommend you take a look through the beginner’s tutorial, and even better, go through @martahedl’s comprehensive BATMAN tutorial.