Is there any information available in the mattermost log file? How about in the developer console (ctrl+J on Chrome, ctrl+k on Firefox)? It sounds like your server isn’t starting correctly.
I am having the same problem. It need to refresh the page 50+ times to gain access to mattermost. This all started when I upgraded from 4.5 to 4.7. There are other minor issues, like for example, the new unread messages feature doesn’t exist in our version of 4.7. There just isn’t a setting for it. So I’m wondering if the installation is broken. However, I re-upgraded (by replacing the mattermost folder with the latest version and copying over the old settings) and the problems remain.
The console in Firefox is reporting this: TypeError: t is not a function [Learn More] root.jsx:69:12 window.onload
Edit: Nevermind. I found the culprit. It was the Firefox plugin passff for my password manager. Time to find a new password manager I guess.