no article defined or the page doesn't exist

Hello,

Please provide your Terms & conditions block setting via a screenshot, AND your relative article setting as well.

Hi,

It could be that the article you've selected is restricted to another language than the current language on your frontend, or that its "access level" setting is restricted to some user groups and that the current user on the frontend is not linked to these, or maybe something along these lines.
That's why Philippe asked for screenshots of the article settings and of the Checkout Terms & conditions area so that we can see if there is anything strange in there.
If @totama didn't answer to Philippe, I would assume that he found the issue with his article while looking at making the screenshots.
So please provide these screenshots.

Hi,

Note that if it happened after an update, it could be a setting issue in the HikaShop configuration. Years ago, we changed how to select the article for the terms and conditions under the checkout tab of the HikaShop configuration. So I would recommend checking there.

If you're not sure, please provide screenshots of the article settings and of the Checkout Terms & conditions area so that we can see if there is anything strange in there.

Hi,

Thanks.
I think I understand the problem. I think it comes from a change on how the parameters in the URL are handled by the router of Joomla 5. I've made a patch which should fix the problem.
Download again the install package of HikaShop on our website and install it on yours to get the patch and it should then work.