# X_LLM_STREAM_INVALID

## Means

a streamed answer failed its output schema, and a stream cannot repair

## Typical cause

`.stream()` on an `llm()` whose `output` the tokens did not satisfy. Distinct from `X_LLM_OUTPUT_INVALID` because there is no repair turn to have failed: the consumer has already read the tokens, and replaying a second answer over the top is two answers to one question

## Fix

call the action instead of `.stream()` when the answer must satisfy a structured schema — a stream has already delivered its tokens and cannot take a repair turn

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