# X_VECTOR_DIM_MISMATCH

## Means

embedding dimensions differ from the store

## Typical cause

the embedder model changed, or the provider returned a width the embedder was not declared with. The fix used to name `x ai reindex`, which is **planned and throws** — a fix line naming it sends an operator to a wall

## Fix

use the same embedder that created the store, or re-embed every record at the new width and upsert it — for a declared/returned mismatch, set `dimension:` on the embedder to the width `cause` names first

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