Ads.txt warning: what should be checked before editing the whole site?

Focuses ads.txt troubleshooting on root URL, publisher ID, hostname, and cache before unrelated site changes.

An ads.txt warning often sends people into broad site cleanup, but the first check should be mechanical: does the root URL serve the file, does it include the exact publisher ID, does the www or naked domain differ, and is a cache serving the old version? Content quality matters for approval, but it is a different question. What is your shortest ads.txt troubleshooting order?