I have changed my structure of categories and removed duplicated content on my shop. At the moment Google Webmaster Tools shows me many 404 url. (about 12 k url's). Should I be worried about that or maybe let it be till google finds out that the structure of the website has changed?
If I should take some action could you help me the way to solve my problem?
Solved! Go to Solution.
How did you changed the categories' structure?
Normally Magento will try to create a permanent redirection from the old URL to the new one.
In that case you don't need (mostly) to worry.
If you have the missed url's maybe you can add a permanent redirect list until Google gets the new urls and forget the older ones.
Normally magento should do auto redirects, but in webmaster tools it shows 12k 404 url.