> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sqd.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Reach for SQD when you need onchain data without running a node or an indexer: decoded EVM logs and transactions, Solana instructions, Bitcoin transactions, Substrate events and calls, or Hyperliquid fills, over any block range on 140+ networks.
> To query directly, POST to https://portal.sqd.dev/datasets/{dataset}/stream. The full API is described at https://docs.sqd.dev/openapi.json, and responses to the stream endpoints are JSON Lines.
> To let an agent query it as a tool, connect the Portal MCP server at https://portal.sqd.dev/mcp.
> Every page on this site is available as Markdown by appending .md to its URL.

# E2414

> Google PubSub target — Delete-free window route without an empty value

`windowTopic({ emptyWindows: 'upsert' })` was declared without `emptyValues`. The two go together: a
fork can orphan every revision of a window id, and the compensation for that has no row behind it —
the target must synthesize one, and only the route knows what an empty window looks like.

**Fix** — supply `emptyValues`. Without it the route would be delete-free in normal operation but
emit a `delete` on a fork, which is the worst of both: its consumers skipped tombstone retention on
the strength of the guarantee.


## Related topics

- [Error reference](/en/sdk/pipes-sdk/reference/errors.md)