Before this blog had the following URL structure /yyyy/mm/dd/sample-post/ ex: /2018/09/05/sample-post/ . Most online newspapers follow this URL structure. It’s great when the blog creates a lot content.
Over time, I figured out my posts still had visitors years after. In terms of SEO, search engine may not directly penalize in their algorithms but people will naturally look for content with a recent date.
More over, I often updated old posts . So I had to change the permalink structure.
I removed the date in the URL so the permalink changed from /2018/09/05/sample-post to /sample-post
Someone liked your old post and shared the link . Now this link doesn’t work anymore , it is broken. You have to redirect the old URL to the new ones.
The redirection must be permanent , use the HTTP code 301 . A 302 is a temporary redirection. I use the plugin redirection .
You could redirect URL one by one, it will be time consuming. Better use a regular expression ( regex ) . Mine is
^/\d{4}/\d{2}/\d{2}/(.*)
/$1/
Yoast redirect tool is a great tool to figure out the regex from your old permalink structure to the new one.