Upgrade from 8.0 to 8.1; sld_hub.vhd error

Responding to FvM's comment, I was guessing that the megafunctions directory was a subdirectory of the project directory and not the Quartus installation directory like C:\altera\81\quartus\libraries\megafunctions. I've been given .qar files that had a megafunctions directory under the project directory. I didn't get such a directory when I tried a test case, but I'm pretty sure it comes from enabling "Include functions from system libraries" in the "Archive Project" dialog box. When megafunctions change between Quartus versions, using this project-archive option can cause trouble.