The problem appears to be that the path was not handled correctly. The backslashes used for the path in windows were interpreted as escapes and I got "\\x08in" and not "\\bin".
I changed this in row 125-127 in pyfr\backends\openmp\compiler.py # If an exception is raised, load from the original path except OSError: escape_dict={'\a':r'\a', '\b':r'\b', '\c':r'\c', '\f':r'\f', '\n':r'\n', '\r':r'\r', '\t':r'\t', '\v':r'\v', '\'':r'\'', '\"':r'\"'} new_string='' for char in lpath: try: new_string += escape_dict[char] except KeyError: new_string += char lpath = new_string return CDLL(lpath) This seems to work! Now I got this problem instead KeyError: <class 'numpy.int32'> as described here: https://groups.google.com/forum/#!searchin/pyfrmailinglist/KeyError$3A$20%3Cclass$20$27numpy.int32$27%3E%7Csort:date/pyfrmailinglist/UYBMh6Uf-qI/AIW3NnRLIQwJ -- You received this message because you are subscribed to the Google Groups "PyFR Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an email to pyfrmailinglist+unsubscr...@googlegroups.com. To post to this group, send an email to pyfrmailinglist@googlegroups.com. Visit this group at https://groups.google.com/group/pyfrmailinglist. For more options, visit https://groups.google.com/d/optout.