Should there be any issue copying "Library" folders to an external hard drive?

[jenny.silver]

Seems my computer may get confused because after copying folders I am unable to mount the external hard drive again, making it corrupt and unaccessible.

 

[Bigwaff]

Per post title… I would think not, macOS will ignore the copy… but why copy the “Library” folder specifically?

 

[Fishrrman]

Are you just "copying" the original folders to another drive...
or
Are you also erasing "the originals" AFTER you make the copy?

Those folders "are where they are" for a reason.
They would be best left alone.