It seems something has changed lately within WordPress and for a lot of users when WordPress cannot communicate with the database (due to rate limiting) then it displays the WordPress installation page - which is slightly confusing! Whereas before it would be an endless loading page, bad gateway error or the correct “Unable to select / connect to xyz database”
When your free account exceeds the hourly database limitations which are set on the free plan, your database is simply frozen, no actions can be made during the frozen time - the database will be paused where it exceeded and resume after a number of hours depending on how many requests you exceeded the hourly limit by.
This is where WordPress can get confused and fair enough depending on the limitation it may see the database but can’t select the tables or it just won’t be able to connect to the database at all - sometimes it will see an empty database - despite your perfectly working database being there - but it is just “frozen” due to exceeding the limits which is why it displays the installation page.
This error can be annoying while you are developing and some users have even went as far as re-installing by accident due to the page appearing! So if you see the WordPress installation page appear on your WordPress powered site and you are positive you’ve already installed WordPress - then please don’t attempt to reinstall thinking this will restore your site access or waive the free limitations which have frozen said database.
Simply wait the rate limiting period out - then your site will return to normal and appear as it did exactly before your website exceeded the free limits.
For instance being if the hourly limit is 5000 requests, if it “costs” 50 requests to load one page then as an example this would likely work out to be 100 pages can be loaded an hour before you hit the limitations and your database is frozen - depending on the amount of requests exceeded the frozen period of time can vary between 10 minutes - 4 hours+ - it really just depends on the amount exceeded.
The bad news: we can’t look into user cases and tell you how long is left - you just need to wait it out - no matter what. If your limiting exceeds 4 hours then it would be recommended to rename the plugins folder to plugins-test to see if this restores access sooner (it may not work) only where your website is exceeding 4 hours rate limiting. If your website appears frozen for more than 48 hours - you may contact us and we can check there is nothing wrong on our side - but it 99% percent is just a waiting game
The example of 100 pages, means within an hour if you loaded 80 pages in wp-admin and a user visited your website and loaded 20 pages or 1 page - 20 times then your hourly limit will be met and you’ll be frozen.
There issue affects new installations more - as if you installed WordPress at 1PM then the installation itself will eat a lot of your hourly database requests, so it would be recommended to wait until after 2PM before you start making heavy backend changes, loading plugins/themes etc as you’ll be frozen fairly quickly sadly.
You can sort of roughly monitor using Query Monitor - https://en-gb.wordpress.org/plugins/query-monitor/
It will give you a rough idea of how many requests you are using in the backend just navigating around wp-admin and the frontend too.
I recommend installing this plugin where possible on the free plan only as paid plans are unaffected by this issue due to having no limitations unlike free system does.
Ensure you “Disable Heartbeat” on all locations.
This helps you lower requests a little bit to save you meeting the hourly limit as quick as you would normally - this should help the majority of free plan users facing rate limiting - other “heavy” users will need to simply wait it out, upgrade or use alternative hosting to avoid issues.
See this tutorial with changing the installation page displayed to users -