Since yocto 2.1, the getVar function in bitbake/lib/bb/data_smart.py doesn't have a default value for the parameter 'expand' anymore. Because of that, meta-openembedded layers throw a lot of ExpansionError exceptions, saying getVar() missing 1 required positional argument: 'expand'.
See also https://bugzilla.yoctoproject.org/show_bug.cgi?id=3314