internal server error 500 on my translated page

Hi,
My default language is English, after changing the language to Bulgarian the current page is translated seamlessly. But then on every page I choose it gives me an internal error of 500, even if I reload the same page it still gives me the same error. I have no such problem with my English(original) pages. I haven’t had such a problem before, I’m not making major changes to the site. I would be grateful if you could give me some guidance.
Good day!!!

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