There isn’t a path maximum per se, but depending what you are doing and what is in your file, there are certain things that can go wrong.

What types of things can go wrong depends mostly on what it is that you are doing. There are different things that can go wrong if you are driving from a PC versus a raspberry pi, and there are different things that can go wrong if you are using the Inkscape plugin versus the CLI versus third party software.

If your file has extremely nested objects — like groups of groups more than 500 deep — you can run into certain types of recursion limits in the software, depending on which software you are using.

If you are working from a PC, check to make sure that it hasn’t gone to sleep.

In addition to not saying what type of computer or software you’re using, you haven’t said what happened when it quit. Do you mean that Inkscape quit, that something crashed, that you got an error message, or something else?

If you’re working from our Inkscape, python, or CLI based software, you might try running a plot preview. Doing so should reveal if any kind of memory limit or parsing error is encountered in the file.

You might also consider contacting tech support directly by email, so we can work on debugging with you. If it’s a particular file that’s causing an issue, we may be able to identify what the cause is.

If the AxiDraw returned to the home corner, then it sounds like the plot finished *normally* in some sense.

My best guess is that one of the following things happened:
Either (1) the software either determined that there was no more data to plot and returned home or (2) the entire plot ran, but the pen wasn’t touching down for part of it. (If you were asleep, then that allows for that second possibility as opposed to quitting in the middle.)

For (1) you should run a plot preview to make sure that everything that you expect to plot renders correctly in the plot preview. If there are parts of the document on a non-printing layer, outside the printing bounds, issues with interpreting the file or planning motion for it, or other similar things, this should catch them.

For (2), it could be that the pen isn’t touching everywhere it needs to in the file (if so, it will seem to “fade” as it more lightly touched the parts near to those missed), that the pen-lift servo motor isn’t working reliably, or that the pen ran out of ink or dried up.

One test that you could do to determine the difference between these (if everything else seems okay) would be to try and run the same plot with the pen-lift servo disconnected on the left side of the machine, so that the pen is down for the entire travel. If there’s a question as to whether the entire path was drawn (but the pen up/down wasn’t working), this could answer that question.