If you are lucky enough today, you might have noticed the new Site Contents page. It appears if your SharePoint online version is 16.0.532.1205 or above. You can find out which version you are running by putting the following in the URL:
This new page is similar to the new Document library pages Microsoft have implemented. The new pages also have lost the ability to run scripts on the page.
In the bottom left of the page, there is a link that states “Return to classic SharePoint” when this is clicked, you return back to the Site Contents we all know and love. (Love might be a bit strong).
However, after I clicked the link, I couldn’t see any way of turning it back to the new Site Content look and feel. How does SharePoint know to display all Site Content pages in classic mode?
It turns out there is a session cookie called splnu set to the value of 0. When this is set in the cookies it displays the old look. Just by closing the page down and re-opening it removes this cookie and then displays the new look and feel again. You can prove that it is this cookie by using chrome tools.
Open the site in Chrome. Switch to the classic mode by clicking the link in the left hand bottom corner of the screen. If you refresh the page, you stay in classic mode. Open the developer tools (F12), and swtich to Resources and expand the Cookies section.
Click on spInu and click delete, then refresh the page. The page reverts back to the new look and feel.