# X_UI_DIFF_SIZE_MISMATCH

## Means

`ui.diff` was handed two captures of different sizes

## Typical cause

two viewports, or `fullPage` on one and not the other — a page that grew is a taller picture. `cause` and `meta` name both sizes; nothing is compared

## Fix

photograph both at one viewport with one `fullPage` setting — `ui.shot` with the same `viewport`/`width`+`height` — then diff those two

[MCP and AI](/error-codes#mcp-and-ai)