Hello,
I found some bug on the split / paginated articles after joomla upgrade from 3.7.5 to 3.8.
"real world" example - article with split pages (intro page): http://www.razersite.eu.org/testy/65-recenzja-podkladki-razer-goliathus-speed-cosmic-large

When you click on 2nd or 3rd link (http://www.razersite.eu.org/testy/65-recenzja-podkladki-razer-goliathus-speed-cosmic-large?showall=&start=1) called "W działaniu" or "Podsumowanie" - it display a custom joomla 404 error page.

The only link from this menu that fully works is the last link (show all pages, "wszystkie strony"): http://www.razersite.eu.org/testy/65-recenzja-podkladki-razer-goliathus-speed-cosmic-large?showall=1&limitstart=

I double checked on a local webserv - it fully worked on 3.7.5 version, after I've upgraded it to 3.8 - it displays a 404 error.

Steps to reproduce the issue

Update joomla from 3.7.5 to 3.8, create some article with split pages, click on 2nd (or next) split page, and it show a 404 error page.

Expected result

Redirection to proper "splitted" page number, without displaying 404 not found error.

Actual result

404 page on all splitted page (except "show all pages" link)

System information (as much as possible)

PHP ver: 7.1.7
MySQL ver: 5.6.36

local webserv:
PHP: 5.6.28
MySQL: 5.6.36