You are browsing this article suggests that you are also facing the same problem – Cookies are blocked or not supported by your browser. I had encountered the login failure issue lately. You must allow cookies to use WordPress. When I met the login obstacle with one of my WordPress websites, I examined login status of my other WordPress websites. I could login to my other WordPress website in the same browser without any error. It was explicit that browser communication by the site is not in the right order.
For the first time was I facing such login error. I had no idea how to resolve it. Therefore, I decided to recollect all modifications I made to the website in last twenty-four hours. Just a day before, I had reconfigured Cloud Flare page rules for the site to improve caching. That led to the login failure.
► Cookies are Blocked – WordPress Login Failure Solution
Since I could identify the real problem – finding, the right solution was easy. I logged-in to my cloud flare account, set the website in development mode. That means I disabled the cloud flare control for the site. Boom, I could easily log in to the website now and access to the dashboard. After I successfully log in to the website dashboard, I went back to my cloud flare account and disabled the active development mode. One smooth action solved the login problem instantly.
I bought this to your notice because when I faced this problem and searched online for an easy resolution, there was none. Instead, there were many ghastly answers. Someone had even suggested making changes in the .htaccess file. Many others were proposing to make some changes in wp-admin files. Those are tricky solutions, developer grade modification. Your website would crash if execute such advanced alteration without having prior experience. My solution whereas will work cent-percent, if you are using Cloud flare as the primary DNS network.