Wait, isn't all the previous editions missions available and isn't there a porting document to update to 5th?
I don't know if all the previous adventures are available - I have most of the stuff from my early days in print form, and haven't had to look.
The only documents I know of take one from 3rd to 4th, and 4th to 5th, not, say, 1st or 2nd to 5th. And they only really handle core rulebook to core rulebook, not supplements. So, if your character was, say, an Magical Initiate, there's problems. And even with a document, converting takes work and time.