WordPress Must Enable Cookies Warning
You’ve had this problem and it has driven you crazy, hasn’t it?
ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.
Here’s a possible solution:
You might have accidentally copy/pasted a carriage return into your site URL or home field.
It took me a while to figure it out, but I finally deleted*, then re-typed each character into these fields.
Problem solved. No more cookie alert.
*make sure to CTRL+A and Delete to make sure no remnants remain in the field.
Update: there can be a lot more to this issue. Take a look at this recently updated thread on WordPress.org.
Update 2: make sure to clear cookies, close all browser windows and try again. If that doesn’t work, read the thread above that links to WordPress.org.