Site health

Site health reports how your sites perform and whether they are throwing errors. Open Sites in Settings and choose Site health: two tabs, Performance and Errors, share one period selector. Both read events the tracking snippet already collects, so there is nothing to set up beyond installing it.

Performance

Performance reports Core Web Vitals at the 75th percentile (p75) for the period, computed from the web_vitals events the snippet already collects on modern browsers. Five tiles cover the three Core Web Vitals, Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS), plus two supporting metrics, First Contentful Paint (FCP) and Time to First Byte (TTFB).

Each tile carries a rating badge using Google's standard thresholds: Good, Needs work, or Poor. Below the tiles, a Slowest pages table ranks paths by LCP p75; a path needs at least 3 LCP samples in the period to appear.

Errors

Errors reports uncaught JavaScript errors and unhandled promise rejections, grouped by message, for the period. Two tiles head the page: Total errors and Affected sessions. A clean report here means visitors are not hitting script errors; there is no configuration required to start collecting them.

The table below lists each distinct error message with its sample location, occurrence count, affected sessions, and when it was last seen.

Sampling, in one place

If your workspace is being sampled (see Overview for when that happens), every report that counts occurrences, page loads, error occurrences, goal conversions, treats each sampled row as 10 events to estimate the true total. Anything counted as distinct people or sessions, visitors, sessions, affected sessions, is always observed directly and never multiplied. Server-captured data, like the click identifiers behind Paid campaigns, is never sampled at all.