broken after update about vim-session HOT 1 CLOSED

Sorry, this is caused by a recent change:

From the readme:

Please note that the vim-session plug-in requires my vim-misc plug-in which is separately distributed.

From the vim-misc readme:

The vim-misc plug-in contains Vim scripts that are used by most of the Vim plug-ins I've written yet don't really belong with any single one of the plug-ins. Basically it's an extended standard library of Vim script functions that I wrote during the development of my Vim profile and plug-ins.

In the past these scripts were bundled with each plug-in, however that turned out to be a maintenance nightmare for me. That's why the miscellaneous scripts are now a proper plug-in with their own page on Vim Online.

Because the miscellaneous scripts are no longer bundled with my Vim plug-ins, users are now required to install the miscellaneous scripts separately. This is unfortunate for users who are upgrading from a previous release that did bundle the miscellaneous scripts, but I don't see any way around this. Sorry!

So please install xolox/vim-misc as a separate plug-in and it should work.

from vim-session.