Error 'OS error - A device which does not exist was specifie

[mdx01]

I ripped a BD to an external USB drive, makemkv failed to create the mkv with this message:

Error 'OS error - A device which does not exist was specified' occurred while reading '/BDMV/STREAM/00002.m2ts' at offset '4493537280'
Error 'OS error - A device which does not exist was specified' occurred while reading '/BDMV/STREAM/00002.m2ts' at offset '4493537280'
Failed to save title 0 to file D:/Videos/Bullitt_t00.mkv
0 titles saved, 1 failed

Is there anything I can try?

[mdx01]

Issue resolved by copying the BD folder to PC drive, so there must be some issues from PC accessing the external USB drive.