One MediaWiki 1.27 wiki fails with "XML is wrong"

[nemobis]

All seems good at https://www.wikihoster.net/whn/Spezial:Exportieren/Main_Page , yet:

Titles saved at... wikihosternet_w-20180506-titles.txt
1059 page titles loaded
Retrieving the XML for every page from "start"
    In attempt 1, XML for "Main_Page" is wrong. Waiting 20 seconds and reloading...
    In attempt 2, XML for "Main_Page" is wrong. Waiting 40 seconds and reloading...
    In attempt 3, XML for "Main_Page" is wrong. Waiting 60 seconds and reloading...

[vgambier]

Same deal with this wiki: https://www.mariowiki.com/Special:Export/Main_Page

Perhaps this instance is related to #241, as it seems https://www.mariowiki.com/Main_Page redirects to https://www.mariowiki.com/