On linux, all the upgrade tests just passed for me with the single exception of MKCL. I don't know what's going on with the following:

; Upgraded ASDF from version 3.0.3.0.1 to version 3.1.0.116 ;; ASDF, version 3.1.0.116 ;;; Warning: The following packages were referenced in compiled file (/home/rpg/common-lisp/asdf/bu\ ild/asdf.lisp) but do not exist yet: (ASDF/PARSE-DEFSYSTEM). Testing it Excessive universal-error-handler depth! Probable infinite recursion! Quitting thread: #<thread "Initial" active (17807) 0x2aead6b02a80 0000000002a82000>. Error while trying to load definition for system test-asdf from pathname /home/rpg/common-lisp/asdf\ /test/test-asdf.asd: Error while trying to load definition for system test-asdf from pathname /home\ /rpg/common-lisp/asdf/test/test-asdf.asd: Error while trying to load definition for system test-asd\ f from pathname /home/rpg/common-lisp/asdf/test/test-asdf.asd: Error while trying to load definitio\ n for system test-asdf from pathname /home/rpg/common-lisp/asdf/test/test-asdf.asd: Error while try\ ing to load definition for system test-asdf from pathname /home/rpg/common-lisp/asdf/test/test-asdf\ .asd: Error while trying to load definition for system test-asdf from pathname /home/rpg/common-lis\ p/asdf/test/test-asdf.asd: Error while trying to load definition for system test-asdf from pathname\ /home/rpg/common-lisp/asdf/test/test-asdf.asd: Error while trying to load definition for system te\ st-asdf from pathname /home/rpg/common-lisp/asdf/test/test-asdf.asd: Error while trying to load def\ inition for system test-asdf from pathname /home/rpg/common-lisp/asdf/test/test-asdf.asd: Filesyste\ m error with pathname: #P"/home/rpg/common-lisp/asdf/test/test-asdf.asd". Cannot open file OS Explanation: (errno == 24) Too many open files

When I start up MKCL, and push /home/rpg/common-lisp/asdf/ and /home/rpg/common-lisp/asdf/uiop/ onto asdf:*central-registry*, then (asdf:component-pathname (asdf:find-system "asdf")) does the right thing and (asdf:load-system "asdf") completes, returning T, and afterwards (ASDF:ASDF-VERSION) returns 3.1.0.116

So it seems like this might be a bug with the test infrastructure, instead of a bug with the actual upgrade.