Just noting that https://phabricator.wikimedia.org/T331228 is very likely caused by this as well. (Bug report is closed, and according to https://github.com/edwardspec/mediawiki-extension-JsCalendar/issues/7 it's not the fault of the extension)

In T311053#8025572, @Aklapper wrote:

Does that still happen after fixing the Uncaught TypeError: btn is null error on that page when being logged out?

In T311053#8019538, @Nikerabbit wrote:

I don't even see a language selector on https://dragontamer.miraheze.org/wiki/Main_Page

In T298708#7700750, @Yaron_Koren wrote:

Okay, now I understand the problem. I'm not totally surprised that the form isn't working - this is a 3000-line file! And if anything, that understates the size of it, because some lines contain more than one template parameter. It basically comes out to something like a 25 x 150 table of data, all contained on one page. It seems to me that you've basically run into a limitation of the software. I would strongly recommend splitting up this data - so that each call to the "DragonData" template is on a separate page.

In T298708#7698835, @Yaron_Koren wrote:

That "form edit" link no longer works (it gives a 502 error) - how can I see the problem?

In T298708#7685458, @RhinosF1 wrote:

Yes, @Xenareee: are you still seeing this?

In T298708#7602188, @RhinosF1 wrote:

Hi, @Aklapper: I'm going to stall this for the moment. We are currently as advertised via Sitenotice experiencing slowness due to our infrastructure migrations.

We can reopen this if it's still happening after we switch to the new DC (late next week or early the week after).