Some of the products url gives 404 error to crawl url, if that product is enabled and visibility set to catalog, search. Also i found there is some product randomly giving 404 error to crawl.
I have checked products in admin and is enabled with stock set. I checked the URL rewrite section but couldn't find anything. Also, tried reindexing everything, but couldn't resolve the issue. Even flushed the cache still nothing.
If i hit the particular product url, its working properly.