Please post a screenshot of the page and the precise urls you obtain for the pagination links (SEF off and SEF on)

Attached are the two screenshots of the relevant settings. The URL for Page 2 generated by the Joomla engine is [https://paragraphos-test.pecina.cz/?id=8&start=6], while it should be [https://paragraphos-test.pecina.cz/?view=category&id=8&start=6]. Please let me know if you need any more information.

1. A category list menu item does display the correct pagination in a clean Joomla site.
2. Your site is weirdly done.
   Links as https://paragraphos-test.pecina.cz/?view=category&id=8 do exist in the module displayed in the left column under the header Kategorie => Humor.
   When displayed and using pagination https://paragraphos-test.pecina.cz/?view=category&id=8&start=6 works fine
   These are not links to category list but blog.

Also these links are really ugly and do not look at all as clean joomla links, SEF on or not.
Here when using the Articles Categories module as you did, I get for SEF off for example:
root/index.php?option=com_content&view=category&id=67&Itemid=571
and when sef on
root/user-modules.html

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/20319

Closed as stated above seems no Core-Issue.

@tompecina Please ask help on the forums. This repository concerns in first Place Joomla-Core coding.

It seems you tested on my test site (paragraphos-test.pecina.cz) when it was already patched and thus obviously you could not reproduce the bug. If you're interested in retesting, the test site (paragraphos-test.pecina.cz) is now left unpatched and the live site (paragraphos.pecina.cz) is patched so you can see the difference.

Otherwise, I've fixed it using my patch and I'm closing the issue for myself too. Thanks for your time!

Set to "open" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/20319

Reopened to find out if its a Core-Issue. @tompecina Thanks for Update.

BTW, if your home page is a category list (or blog), a url like
mydomain.com/?start=5 is perfectly OK

Right, but not for any other category, which is the case here.

As I said above your links in the categories module are weird and are not the default ones we obtain with a clean Joomla.

You get
?view=category&id=8&layout=
I get here

index.php?option=com_content&view=category& etc.

You have modified something somewhere (extension, else) which creates this apparent issue.

You have modified something somewhere (extension, else) which creates this apparent issue.

I did not modify the code in any manner (this patch is the first I applied), all I did is I toggled the URL-related controls several times before I got the URLs I liked. Which, unfortunately, I cannot reproduce because I don't remember the order of the changes.

You may not have modified joomla core code, but you may use 3rd party extensions which impact the normal Joomla Routing system.
For example, you use JComments (I do not know if that one is at stake).

You may not have modified joomla core code, but you may use 3rd party extensions which impact the normal Joomla Routing system.
For example, you use JComments (I do not know if that one is at stake).

I removed all the third-party extensions from the test site now, but the result is the same: the category list (eg: Humor still produces broken pagination links.

Give me access to your test site by sending superuser credentials at infografjms arobase gmail.com and I will have a look. I am still convinced that something is modified in your test site.

I sent it to arobase at gmail.com: I hope I got the address right!

https://fr.wikipedia.org/wiki/Arobase 😄

Sorry, was in French...

You are using Modern Routing.
In this case, one should always add at least a hidden menu item to All Categories.
I did this on the test site and now you will get urls of this type from the categories module
https://paragraphos-test.pecina.cz/all-categories/nase-pripady/adam-b-bartos?layout=

and pagination https://paragraphos-test.pecina.cz/all-categories/nase-pripady/adam-b-bartos?start=10

The &layout= issue has been solved in current code ( #20229 ) and will be in next J release.

Please delete the special account you created for me.

Tested & implemented on the live site - thanks!

@tompecina if this Issue is resolved please close it.

Long time I wanted to test Olomoucké tvarůžky
do not hesitate. :)

I've never tasted these (and no, I don't drink beer, for that matter) :-)

hehe