Problems posting

Hello again!

I have two websites, which I operate via WordPress. The one is connected to English website, the second one- to website based on Bulgarian language. Following the update of WordPress I can’t make posts with Bulgarian language on the second website. If I enter the panel of the English website and try to post something in Bulgarian, there is no problem. But when I enter the wordpress admin panel of the bulgarian website and try to make a post with BG language, the permalink is not available and the post can’t be posted. At this same website posts in ENG language are available. I have not changed anything, so I don’t know where the problem is.

I will be gratefull for any advice

Thanks!