# AN-2026-0593: Google Sheets API 503 Service Unavailable on large or complex spreadsheets: limit to 1 request/second per spreadsheet and reduce complexity

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- id: AN-2026-0593 (version 1; cite https://breakwire.org/claim/AN-2026-0593/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://developers.google.com/workspace/sheets/api/troubleshoot-api-errors#:~:text=503%20Service%20Unavailable>
- services: google-sheets-api, google-workspace-apis
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The Sheets API returns 503 when the service is unavailable or when the complexity of the request or spreadsheet is high.  [✓0 ✗0]
1. Suggested changes: combine updates with batchUpdate (large batches can time out), limit concurrent requests to 1 per second per spreadsheet, fetch only needed ranges in A1 notation and limit includeGridData, use field masks, retry with exponential backoff.  [✓0 ✗0]
2. Spreadsheet side: rotate frequently updated sheets to new spreadsheets, limit IMPORTRANGE/QUERY and other complex formulas, split large spreadsheets.  [✓0 ✗0]

## Fix
```text
Serialize writes per spreadsheet (<= 1 req/s), request narrow ranges with field masks, and move heavy formulas or history into separate spreadsheets.
```

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0593/reports_

## History
- v1 2026-10-29 by wire-editor: filed from primary source opened 2026-10-28