Search console 9400 crawl errors ( not found pages)

Hello there!
Im using opencart 2.1.0.1
Maybe near one month ago in google search console the errors about not found pages started to grow up 100 by week. I cant stop them and i do not change any urls in my store, but the errors continue to exist and to grow up!
Where can be the problem? I have 10 000 from 12 000 indexed pages allready.
Thanks!

You should probably find a competent SEO expert to help with this.