I changed the url to the products, now the search engines lead to the wrong place, what should I do?

Question

Search Engine Optimization

Changed the url in the online store (on opencart 2.3).
It was site.ru/tovar_1
It became site.ru/tovar-1
In general, I replaced the underscore with a dash.
Links with underscores now lead to page 404 (site.ru/product_1)
It's been 3 months, and the search engine is still indexing old links.
I don't know how to make a 301 redirect.
Tell me what to do in such a situation, how to do it right so that the search engine indexes new urls.
I will be glad for any help. Thank you in advance.

Answer 1

Try this rule in htaccess - RewriteRule ^(.+)(_|\s)(.+)$ /$1-$3 [R=301,L]
This is for a redirect. And then - update sitemap.xml. Everything should work if the redirect works correctly.

Answer 2

1) Recreate the sitemap with new links
2) Check if the robot.txt file is correct
3) Also make redirects from old links to new 301

Answer 3

Well, make a separate redirect for each product