I normally use SW2018.
I downloaded SW2019, opened a few assemblies, and then left it alone. Lesson learned... I'll wait until SP1 to actually use it.
An assembly I saved in SW2019 won't open now in SW2018, and I need it to. Is there any way to go back in SW2019 and save it with compatibility with SW2018?
I was under the impression this problem was fixed a few versions ago!
I done this in the past. The best way I sorted it out was to restore the file to the previous version.
R/H on the file in question & select 'Restore Previous Versions' It should show you the file prior to when it was saved.