language_update_1000 in core/modules/language/language.install

Rename {language}.language to {language}.langcode.

node_update_1001 in core/modules/node/node.install

Rename node type language variable names.

node_update_1003 in core/modules/node/node.install

Move theme settings to global site configuration.

system_update_1001 in core/modules/system/system.install

Move from the Garland theme.

system_update_1002 in core/modules/system/system.install

Set Bartik as default theme if it implicitly was the default before.

system_update_1011 in core/modules/system/system.install

Specify the files directory manually if needed.