A line that is not this format
Parse errorThe file could not be read. Nothing is converted until the line is corrected.
What the converter says
line 6 is not anything this format has: ???
What triggers it
Every line of an MPR is a block, a macro, a contour, an element, a value or the closing mark. This one is none of them. Rather than skip it, the converter stops: a line nobody recognised is how a reader quietly loses an operation.
[H
VERSION="4.0"
_BSX=800
_BSY=600
_BSZ=18
???
How to fix it
Look at the line named. A stray character, a line wrapped by an editor, or a file that is not an MPR at all are the usual causes.