Joomla Blank (white) admin screen - not possible to load backend
This error happens quite often if you upgrade your version of Joomla.
Once the upgrade completes, the admin area page is white, with nothing else displayed. It is quite often the case that the frontend (public) part of the web site is working as normal.
The issue is usually caused by an out-of-date or incompatible admin component or module. To see which one is causing the issue on your site go into your hosting control panel and use the file / directory browser and navigate to your 'public_html/administrator/ folder and open the 'error.log' file.
This should give you a clue as to what is causing the issue, showing you the path to the component or module in your admin area. Once you have identified the issue, simply rename the component or module's folder to something else and then try reloading the admin area of your Joomla site.
If the admin area loads as normal, you have found the problem. You can now decide to see if there is an update to the component / module or uninstall it completely.
If this didn't work for you, please get in touch and we will be happy to take a look for you.