When a visitor click the registration send button it fails and ends up on a 404 page: with this url
This happened after an update of joomla to 3.8.4 today . That could be the reason. Or is there another reason?
I don't know what url is normal after sending the registration form.
Solved, but I don't know how. I deleted JCH optimize pro, because it was generating cache files while it was unpublished (could be a reason). But also I found an old language file from joomla 3.7 that was active, while I use joomla 3.8.4. There was no update about the file (it was already updated). I installed that language file again (dutch) . I reinstalled JCH, Cache cleanend everywhere en everything works fine. Registration en confirmation works 100%. What was the reason? Any idea?