We have a rebuild new website and we have removed all the old pages (dummy pages comes with template) and blocked them via robots txt. now we keep receiving Index coverage issues warnings. Is it safe to ignore or any workaround?
Rather than blocking with
robots.txt it would be better to 301 redirect them. It would also be worth looking into how they got indexed - were they published for awhile and got crawled, or is it possible they are in sitemaps or links somewhere? Google is usually good about dropping off non-existent pages once it receives a solid 404 or 301 for long enough.
Disallowing in robots.txt does not actually stop indexing. It stops crawling. If they are already indexed you will see them reported as index coverage issues. They will continue to be indexed, but Google will not know what they contain.
If those pages should never have existed, which I suspect, you want to make sure they return a 404 or 410 status to say they no longer exist. You will still probably see issues in the index coverage report, but that is exactly what you want Googlebot to think. The pages do not exist.
Only 301 if the content was of any value and the same or similar content is now at another URL.