Choral Public Domain Library

I'm attempting to upload a new edition of a work I posted almost 10 years ago (first of several). All goes swimmingly on the AddWorkForm up to the point when I need to upload a file.
Pressing the "Upload File" button results in the message:

Safari can't open the page "https://www.cpdl.org/wiki/index.php/Spe ... file=score" because the page's address isn't valid.

Attempting the same with the DuckDuckGo browser also fails, but the page goes blank, rather than giving an error message.

Clearly, going further with the AddWorksForm is a little pointless without an uploaded file.

Has anyone seen anything similar?

System is a M2 MackBook Air, running macOS Tahoe 26.2

I'm now trying the Opera browser, which is still failing, but gives a different error message:

This site can’t be reached
The web page at https://www.cpdl.org/wiki/index.php/Special:Upload might be temporarily down or it may have moved permanently to a new web address.

ERR_ACCESS_DENIED

So, from this, it would appear that one of three things is happening

1. the upload page is down
2. the upload page has moved, but the coding on the AddWorksForm hasn't been updated
3. access by my user is denied for some reason.

If 1 or 2 is true, then presumably others have this problem as well.
If 3 is true, then it will take administrator intervention to fix?
If the problem lies with my setup (see original post), then surely others using something similar will have hit that problem?
I did recently successfully upload files on another part of my system (M4 Mac Mini), but I can't remember if that was still on macOS Tahoe 26.1 or had updated to 26.2.

i won't be able to do anything with that part until I return from holiday in a bit over a week's time. (no, Northumberland isn't any dryer than Dorset!)

the upload page is down

No, I use it all the day since years without any problem until now

Our servers are often overwhelmed by crawlers at any time.
Then we get error messages like "server encounter difficulties... wait a few minutes and reiterate..."

When this is too annoying, an "Under attack mode" is activated which asks users to click in a box and generally ticks automatically the box within a second, except if you have been inactive during a few minutes.