I've tried to install the dev version but the item layout page breaks :(
Anyway, I'll wait for the stable 10.3 to upgrade. Now it's kinda of an emergency.

EDIT: Even with the fix from @Bouey it doesn't work so I've figured it out it's due to the K2 Multi Categories override located at /plugins/system/k2multiplecategories/overrides/site/components/com_k2/models/itemlist.php
I'll contact the developer once again to check this thread.

Thanks again.

Yes, it is Fotis

Hello,
same problem here with Falang.
Couldn't make work the patch given by the developer. Is there any new about him?

Hello, I have the same problem. I spoke to the web357 developers and they told me that it was a problem with the falang component, I spoke to the falang developer and he redirected me to this page and I have been looking at the answers and it seems that it can be fixed if you install K2 v2.10.3 (dev). I checked what version I have and it was the same but I reinstalled it in case it was fixed but it still doesn't work and I would like to know what the problem is.

A Greeting

Hello.
I have already installed K2 v2.10.4 (dev) and there is no change, it looks exactly the same. I tried to change the protostar template and it doesn't work either. The only way to set the page is to disable the falang plugin but by doing that you won't be able to translate the web anymore.

A Greeting