# X_MCP_RESOURCE_DUPLICATE

## Means

two resources claim one MCP resource URI

## Typical cause

an app resource registered at a `ultimate://` URI the framework already publishes, or one `registerAll` batch listing a URI twice. Resources used to `Map.set`-overwrite while tools threw, so `resources/read` answered from whichever provider was wired last

## Fix

give one its own URI — `register({ uri: 'ultimate://manifest-<what-it-is>', … })` — or drop the duplicate registration

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