It is related to "Minimal Download Strategy":
The reason why the "Connect to Outlook" is greyed out, is because
there is a feature called "Minimal Download Strategy". The feature
redirect you to an application page start.aspx, do some validation,
and loads start.js script. This add the "_layouts/15/start.aspx" in
the URL wich seems to break the Connect To Outlook functionnality.
To go arround this, you have 2 choice;
1-Open you Calendar, Click the Calendar button in the top navigation
bar, and go to "List Settings". (4 buttons right from the connecto to
From there, copy the "Web Adress", and paste it in the adress bar of
Then go to the Connect to Outlook, it shouldn't be greyed out anymore.
It work for me on IE9 32bit with outlook 32 bits.
2- Go to the site settings of your collection, then to Manage Site
Features, and deactivate the Minimal Download Strategy" feature.
The Minimal Download Strategy is actually a very good feature that you
migh want to keep though as it makes most of the apps load faster.
I still don't know why this breaks it, but I'll do more research on
Let me know if this works for you as well.