support.google.com
Google Search Console — Data Anomalies
Google's official page documenting known data anomalies in Search Console, including the May 2025 impressions logging error.
Google Search Console SEO Pitfall Guide
05/18/2026, 04:27:58 PM@gritty
Your GSC Impression Data Has Been Wrong for 11 Months — Here's What to Do Now
Google confirmed that Search Console over-reported impressions from May 13, 2025 through April 2026 due to a logging error. Clicks and rankings were never affected. Here is the six-step action plan every indie developer should run this week: set annotations, switch to clicks as your primary metric, pause CTR-based title rewrites, cross-check GA4 organic sessions, recalibrate any year-over-year comparisons, and back up your raw GSC data now.
If you've been puzzling over a mysterious CTR slump in Google Search Console, or congratulating yourself on surging impressions over the past year, both reactions may have been responses to a ghost. On April 3, 2026, Google confirmed that a logging error had been systematically over-reporting impressions in the Search Console Performance report since May 13, 2025 — nearly eleven months of distorted data that affected every site owner relying on GSC for SEO decisions.1
For indie developers making decisions alone, without a team to cross-check numbers, this kind of invisible data rot is exactly the pitfall that quietly wastes hours of optimization work.
What the bug actually did
The error hit impressions only. Clicks, average position, and actual organic traffic were never affected. That sounds minor until you realize impressions are the denominator in every CTR calculation.2
With impressions inflated, your CTR looked lower than it actually was. If you responded to that apparent drop by rewriting title tags or redesigning meta descriptions over the past year, you were treating a measurement artifact — not a real ranking problem.
| Metric | Affected by bug? |
|---|---|
| Impressions | Yes — over-reported since May 13, 2025 |
| Click-through rate (CTR) | Yes — artificially deflated (wrong denominator) |
| Clicks | No — accurate throughout |
| Average position | No — accurate throughout |
| Actual organic traffic (GA4) | No — accurate throughout |
To make things messier, a separate event hit in September 2025: Google disabled the
num=100 URL parameter that SEO tools used to fetch up to 100 search results per query. That removed bot-generated impressions from tracking, causing a 40–60% visible drop for many sites. So between May and September 2025, two competing forces were running at once — the bug inflating impressions up, and the num=100 shutdown pulling them down. Separating the effects retroactively is not practical.2The fix is rolling out — and it will look like a drop
As of early April 2026, Google has started correcting the data. Impressions in your Performance report will visibly decrease over the coming weeks as the fix rolls out. This is not a penalty. Your rankings have not changed. It is the dashboard catching up to reality.3
If you're about to present an SEO report to a client, investor, or even just your own records, get ahead of this now.
Six things to do this week
1. Set two annotations in GSC right now
Go to Search Console → Performance → add a custom chart annotation for May 13, 2025 (bug start) and another for April 3, 2026 (correction begins). If you haven't already marked the September 2025
num=100 drop, add that too. Future-you will thank present-you when someone asks why the numbers looked like that.2. Switch your primary SEO metric to clicks — today
Clicks were unaffected throughout. For an indie developer with limited reporting bandwidth, clicks (and organic sessions in GA4) are a more honest signal than impressions anyway. If your GSC clicks and GA4 organic sessions are both stable, your actual search performance has not changed regardless of what impressions show.
3. Pause or revert CTR-based title/meta changes made during the bug window
Any title tag or meta description you rewrote between May 2025 and now in response to a "falling CTR" was responding to inflated denominator data. Before you make further changes, wait until the correction completes (Google estimates several weeks), then re-evaluate CTR with clean numbers.
4. Cross-check your GA4 organic sessions for the same period
Open GA4 → Reports → Acquisition → Session source / medium, filter for
google / organic. If those sessions are flat or growing while GSC impressions were rising, that mismatch is evidence of the bug in your own data. Screenshot it for your records.5. Recalibrate any year-over-year comparisons you've shared
If you sent a report citing Q2 or Q3 2025 impression growth, that figure is inflated. For stakeholders, one sentence is enough: "Google confirmed a logging error that over-reported GSC impressions from May 2025 through early April 2026. Clicks and actual traffic were unaffected."
6. Export and back up your raw GSC data now
Google has already confirmed that data from two days in late February / early March 2026 is permanently unrecoverable from the Bulk Data Export. Treat historical GSC data as perishable. Export your performance data regularly — monthly at minimum — via the GSC API or Bulk Data Export to protect your own audit trail.
The real lesson
2025 was, by any honest account, the most chaotic year for GSC data reliability since the tool launched. The impression bug. The
num=100 shutdown. Multi-day reporting outages. Bulk export gaps.None of these affected your actual search performance. But they exposed a real operational risk for solo developers: when you have one data source and no one to challenge your read of it, a quiet counting error can send you optimizing in the wrong direction for months without realizing it.
The fix is not to abandon GSC — it remains the only direct window into how Google sees your site. The fix is to treat it as one signal among several: clicks and conversions as primary truth, GA4 organic sessions as a cross-check, and GSC impressions as context that occasionally needs an asterisk.
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