What is 404 error in Search Engine Optimization.
When a page URL no longer exists or is renamed, any links directing to the original URL will return a 404 Not Found error. There are common instances that may result in a significant number of 404 errors.
1. Website redesigns
2. Product pages that have been altered, removed, or discontinued a which results in changing or deleting
3. Spelling errors within links a whether internal or external
4. Shifting a website or page from http to https (or vice-versa)
Google is forgiving when it comes to 404 errors. It will not deindex a website due to these errors, and probably will not even directly decrease rankings. 404 errors are inevitable, and Google understands that. However, it’s important to remember that Google’s main priority in organic search is to deliver quality results.
Hope that helps.