Language switcher does not have current page query parameters I have a custom block that shows a schedule. It also show arrows to allow the user to see next or previous days. For this I simply add ?date=DATE to the arrow link. Once landed on one of those pages that have a GET query parameter it is impossible to switch language without loosing your current date selection.

I searched and found many similar issues but all for Drupal 7. 

Switching language loses the line item URL parameter

Language switcher (locale_block) doesn't keep query parameters

Since this part of Drupal have been completely rewritten, I need a solution for Drupal 8.

IMO I think it should be a bug in Drupal 8 core. I think the language switcher should know there is existing GET query parameter that need to be passed along the language links. I don't see any reason you wouldn't want to keep the GET params.

anyone has a solution to this problem?
It seems that when I upgrade from 8.1.x (8.1.10) to 8.2.x (8.2.6) it fixes the problem. So it was a core bug.