This page should be used to keep track of items which should be added to the migration guide. It's a living document for the life of a development cycle and by M4 should represent a significant proportion of items that are worthy of note in the migration guide. Once the migration guide for a release has been completed the contents of this page should be archived in a versioned subpage (i.e. FutureMigrationGuide/2.2)

2.2 Migration Guide items

How we stage directories in sysroot has been simplified and introduces some new variables (SYSROOT_DIRS, SYSROOT_DIRS_NATIVE, SYSROOT_DIRS_BLACKLIST). See the v2 patch series on the OE-Core mailing list: http://lists.openembedded.org/pipermail/openembedded-core/2016-May/121365.html
bitbake now requires python 3.4+
the metadata now requires to use python3 syntax. There are many python3 porting guides out there, or the conversion commits for Bitbake and OE-Core can be used as a guide for changes. Particular areas of note are subprocess command line pipes needing locale decoding, the syntax for octal values changed, the iter*() functions changed name, iterators now return views, not lists and some python modules changed names.
most target python recipes have now been switched to Python 3, unfortunately systems using RPM as a package manager and providing online package-manager support via SMART still require Python 2
Uclibc removed in favour of musl
${B} no longer the default working directory for tasks
We require a UTF-8 locale on the build host. As C.UTF-8 isn't a standard we default to en_US.UTF-8
runqemu ported to Python and changes behaviour in some cases (NEEDS docs)

FutureMigrationGuide/2.2