Should SO check for stale (404) URLs?
53782
Can we have some tools to handle link rot?
52279
Refreshing error pages lead to error pages even after the error is fixed
77994
Any good reason to noindex /page/2/ in archives?
60028
How to tell if a  tag failed to load
69406
Check if file exists but prevent 404 error in console from showing up
44368
404 error during flagging a question
17308
WinterBash site exhibits some strange 404 behavior
61409
How can I check if a URL exists via PHP?
101890
Should we ever check for mysqli_connect() errors manually?
118749
can google index/crawl random subdomains that aren't linked to from anywhere
4336
"404. That’s an error." when viewing from Google cache
51513
More 404s with missing slashes
93300
Asp.Net MVC: requests with too long URLs and error handling
57708
Search for new questions returns yesterday and older posts on most Stack Exchange sites
121625
Do you have to restart apache to make re-write rules in the .htaccess take effect?
106317
Google reports 404 errors on URLs that haven't existed for six months and are no longer linked to on my site
138558
urllib2 returns 404 for a website which displays fine in browsers