Hi,
first at all, copying objects between different versions of AutoCAD is definitely not the way to go.
As already mentioned, open both drawings in the same version of AutoCAD to use copy and paste.
Another method could be to run command _WBLOCK to export your polylines to a temporary dwg-file and then use command _INSERT to insert this file in the older AutoCAD release.
>> why all of a sudden I cannot copy and paste between versions.
>> LT20 to ACAD 20 was fine, LT20 to ACAD 18 was fine. And now
>> after an upgrade it is broken. Why is it an issue now, when it
>> wasn't before?
However .. I have tried with new dwg-files without having any application running to copy objects (tested lines and polylines) from 2022 to 2020 ... working well (using command _COPYBASE and _PASTECLIP).
If that does not work for you then it might depend on the difference of full AutoCAD to AutoCAD LT (which I can't test as I don't have LT) or you have objects or settings in your drawing which block this copy and paste. And as you are working with applications this could be the source of your issue.
Anyway, to stay clean with your drawings please use the suggestions you already got (same AutoCAD version or WBLOCK ==> INSERT).
- alfred -
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Alfred NESWADBA
ISH-Solutions GmbH / Ingenieur Studio HOLLAUS
www.ish-solutions.at ...
blog.ish-solutions.at ...
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CDay 2025------------------------------------------------------------------------------------
(not an Autodesk consultant)