When trying to access 'customizer' inside 'appearance', I get the error in the screenshot.
As far as I know, views works flawlessly everywhere else and so does the site.
However, when de-activating views plugin, the error goes away on a page refresh.
Are you aware of this problem?
I tried re-installing 3.5.3, the problem still existed. So then I updated views plugin to 3.6.1 and the problem still exists.
Also, this is the case on all of my websites, not just this one. Views seems to be causing this error.