I figured it could be useful, to make a post to assist people when they see the “Checking your browser before accessing gitlab.com” message.
Sometimes this message can appear, and like yesterday (11 August 2021), a lot of people were experiencing this because of an outage at Cloudflare that was being resolved. Even today the Cloudflare status page still shows some points being re-routed so the problem today can still occur for some people. This can be region-dependent depending on where you are located, and also it can affect people using Tor Browser as well.
If you are receiving this message, first of all, please check the Cloudflare status page here: https://www.cloudflarestatus.com/
There is every chance based on your location, that a Cloudflare point near to you has some technical issues, which are in the process of being resolved. If this is the case, I would suggest running a VPN that allows you to change VPN location. I personally use Windscribe to do this, but there are plenty of others. For example, when I’ve experienced this with our web application in Central Europe, I run the VPN for United Kingdom and check access. If it works, then I know that the problem is my current location. This might be a bit hit-and-miss, so you might need to check various locations further away just in case otherwise you might end up using the same Cloudflare servers as your normal location if you don’t try a bit further away. In some instances, I might even go as far as USA as a VPN location, or other continents to compare.
This isn’t a Cloudflare misconfiguration error, although sometimes could be if settings within Cloudflare are set a bit too sensitive. But if that was the case, it would be happening all the time when attempting to access Gitlab.
If you are still seeing issues, perhaps your browser is causing the problem, try a different one, Chrome, Firefox, etc. Try normal modes, and also privacy/incognito mode to rule out plugins causing a problem. If you changed the User-Agent string in the browser, reset this to the default one temporarily to see if this helps, and potentially clear browser history/cache.
Usually the problem will be due to an outage at Cloudflare, and will resolve itself within a reasonable amount of time, and sometimes it just means that you need to be patient! It’s not unique to Gitlab, Cloudflare is great as a CDN as well as a means for saving overloading your VPS and bandwidth when Cloudflare can cache for you, as well as protect your servers against various security threats.
Hope that helps for anyone who might be experiencing this again in the future.