A drop has a limited number of causes, and they need different responses. Work through them in order rather than guessing.
1. Is it a reporting problem?
Check whether tracking broke, a filter changed, or the comparison period is misleading. Surprisingly often the traffic never moved.
2. Is it technical?
Check Search Console for a spike in errors, a robots.txt change, an accidental site-wide noindex, server errors, or an expired certificate. Recent deploys are the usual suspect.
3. Is it a manual action or security issue?
Both appear in Search Console. They are rare but unambiguous.
4. Is it an algorithm update?
Check the date against Google update history. If it aligns with a core update, treat it as a quality question rather than a bug.
5. Is it the market?
Seasonality, a competitor launch, or declining interest in the topic. Google Trends distinguishes “we lost share” from “the category shrank”.
Alien Road recommends: always check the deploy log before the algorithm history. In our experience the majority of sudden single-day drops trace to something the team shipped, and the fix takes an hour once you connect the two. Blaming an update first wastes the window in which the cause is still obvious.