Yes you will have to go 21 to 20, then 20 to 19 as a PLN before saving as PLA.
However I don't think this will do anything to convert your library down to 19.
Embedded library objects will save back but not linked libraries.
So if you are linking to library objects created in 21 then they may be missing - I'm not quite sure how the migration libraries work when going backwards.
When you get the file back to version 19 you will see for yourself if the library objects are working or not.
If you are using the GS library then you will need to delete the 21 library and load the 19 library before trying to save as a PLA.
But if you are using the standard GS library there is no need to save as a PLA which means to me you must have your own custom library?
If that is the case and it is compatible with 19 then all should be fine.
If not you will need to find a 19 compatible version.
You will see by the time you get the file to 19 if you have any library issues.
However you definitely will have missing stairs and rails from the 21 file if you used them - as these will not convert back at all.
Barry.
One of the forum moderators.
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