Warning: A browser setting is prevent you from logging in

Help: Enabling cookies

In order to properly log you in, your browser needs to accept cookies from all domains.

Open up Settings > Privacy. Then, make sure Accept cookies from sites is checked. Also, make sure Accept third-party cookies is checked as well.

After closing your settings, you may try logging in again.

Optional: If you would rather add an exception just for Disqus, click Exceptions… and add disqus.com as an allowed domain.

For a fairly long time now, browsers have been configured not to allow third-party domains (or, to use their real name “advertisers”) to set tracking cookies on computers via embedded advertising. Now, in the age of (kinda crappy, JavaScript-dependent) comment widgets like Disqus, it is apparently acceptable to provide blanket instructions to users on how to undo that small step forward in sane privacy settings, because it’s inconvenient for a single piece of their functionality.

That final paragraph about adding Discus as an exception to the blocked cookies setting should be the only paragraph. The rest of it is up there with ‘Hey, just disable your virus scanner’ in terms of lazy idiocy, and to present the entire scenario as an error (red highlight, ‘warning’ language) is completely disingenuous.

If you’re a third party widget of any kind who needs this kind of non-standard, much-abused functionality, you should be asking for permission, not telling the poor user that their system is at fault when it’s not.