When I open the Extension Manager in Inkscape 1.3 on MacOS 10.13.6 I get the following error:

Traceback (most recent call last):
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkman/inkman/manage_extensions.py", line 29, in <module>
    from inkex import gui
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/__init__.py", line 11, in <module>
    from .extensions import *
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/extensions.py", line 34, in <module>
    from .elements import (
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/elements/__init__.py", line 9, in <module>
    from ._parser import SVG_PARSER, load_svg
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/elements/_parser.py", line 30, in <module>
    from lxml import etree
ImportError: dlopen(/Applications/Inkscape.app/Contents/Resources/lib/python3.10/site-packages/lxml/etree.cpython-310-darwin.so, 2): Symbol not found: ____chkstk_darwin
  Referenced from: /Applications/Inkscape.app/Contents/Resources/lib/python3.10/site-packages/lxml/etree.cpython-310-darwin.so (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib
 in /Applications/Inkscape.app/Contents/Resources/lib/python3.10/site-packages/lxml/etree.cpython-310-darwin.so

If I try and save an SVG file as ‘optimised’ the call to Scour will produce the following error:

Traceback (most recent call last):
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/output_scour.py", line 7, in <module>
    import inkex
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/__init__.py", line 11, in <module>
    from .extensions import *
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/extensions.py", line 34, in <module>
    from .elements import (
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/elements/__init__.py", line 9, in <module>
    from ._parser import SVG_PARSER, load_svg
  File "/Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions/inkex/elements/_parser.py", line 30, in <module>
    from lxml import etree
ImportError: dlopen(/Applications/Inkscape.app/Contents/Resources/lib/python3.10/site-packages/lxml/etree.cpython-310-darwin.so, 2): Symbol not found: ____chkstk_darwin
  Referenced from: /Applications/Inkscape.app/Contents/Resources/lib/python3.10/site-packages/lxml/etree.cpython-310-darwin.so (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib
 in /Applications/Inkscape.app/Contents/Resources/lib/python3.10/site-packages/lxml/etree.cpython-310-darwin.so

Is this a problem with my version of macOS being too old? Is there anything I can do to fix this (apart from buying a newer Mac)?

I asked in Chat about any recommendation for Inkscape on HighSierra. Waiting for response.

Aside: what makes you think you need a new Mac for newer macOS?

Thanks! For Inkscape 1.2 there is an explicit macOS version range stated, from High Sierra up to but not including Ventura. I haven't been able to find something similar for Inkscape 1.3.

As for the new Mac, unfortunately this is an 11 year old Macbook and even Apple doesn't support hardware that old. High Sierra is the newest it can do.

leoneo

even Apple doesn't support hardware that old

It´s just Apple and that´s the crux - I know this all too well when they refused to repair an old Mac due to lack of spare parts.

Maybe have a look here: https://dortania.github.io/OpenCore-Legacy-Patcher/

From the one and only Mac-developer in the team:

• If a user on High Sierra relies on extensions (I don't know how many of them require lxml) they need to stick with 1.2.2 for the time being.

Cheers

Great, thanks for finding the answer! It was more or less what I feared. I'll keep it at 1.2.2 until this machine is replaced.