---
title: "VTEX FastStore 4.9.1 returns the original StoreProduct.releaseDate value again: 2026-10-02 | Harbyn"
description: "VTEX FastStore 4.9.1 returns the original StoreProduct.releaseDate value again, announced Oct 2, 2026."
canonical: "https://harbyn.com/changes/vtex/2026-10-02-faststore-restored-the-original-product-release-date-format"
last-updated: 2026-10-02
---

# VTEX FastStore 4.9.1 returns the original StoreProduct.releaseDate value again

Markdown version of <https://harbyn.com/changes/vtex/2026-10-02-faststore-restored-the-original-product-release-date-format>.

Behavior change - VTEX. low severity. In effect.

In FastStore v4.7.0 through v4.8.x the API resolver converted StoreProduct.releaseDate to an ISO 8601 date for every GraphQL consumer. FastStore v4.9.1 returns the original catalog value again (epoch timestamp, another string format or an empty string) and applies ISO 8601 only in the PDP JSON-LD; customizations changed to expect ISO 8601 must parse the original value.

## Facts

| Fact | Value |
| --- | --- |
| Vendor | [VTEX](https://harbyn.com/vendors/vtex.md) |
| Kind | Behavior change |
| Severity | low |
| Status | In effect |
| Announced | Oct 2, 2026 (undated by the vendor; the day it first appeared) |
| Added to Harbyn | Oct 2, 2026 |
| Lead time | No dated deadline |
| Review | Reviewed by a person, extracted by a model |

## Find it in your code

```sh
npx harbyn scan
```

This change names no identifier the scanner can match line by line, so the scan tells you whether your repository uses VTEX, from its packages and API hosts. Nothing leaves your machine.

## Sources

Where this event comes from: the page we read, when we read it, and the hash of that snapshot.

- <https://developers.vtex.com/updates/release-notes> (changelog, fetched 2026-10-02 22:20 UTC, sha256 `f9ad27eade10cdd4f79db73cc9a9c366d74b17a486657810f3c75e5fd21dcc32`)

## Related changes

### More from VTEX

- [VTEX Master Data API v2: schema saves return 423 Locked for 12 hours after a full reindex](https://harbyn.com/changes/vtex/2026-09-30-schema-saves-blocked-after-a-full-reindex.md) (Behavior change, announced Sep 30, 2026)
- [FastStore 4.9.2 fixes session and cart validation failures after region changes](https://harbyn.com/changes/vtex/2026-10-05-faststore-fixed-session-and-cart-validation-after-region-changes.md) (Behavior change, announced Oct 5, 2026)
- [FastStore WebOps previews deactivate after inactivity](https://harbyn.com/changes/vtex/2026-09-17-faststore-webops-previews-deactivate-after-inactivity.md) (Behavior change, announced Sep 17, 2026)
- [FastStore 4.10.0 keeps catalog and preview carts on the correct sales channel](https://harbyn.com/changes/vtex/2026-10-22-faststore-4-10-0-keeps-catalog-and-preview-carts-on-the-correct-sales-channel.md) (Behavior change, announced Oct 22, 2026)

### Changes at other vendors

- [SEFAZ e-invoicing (NF-e, CT-e, MDF-e): NF-e/NFC-e net product value fields and prepaid ICMS group on November 3, 2026](https://harbyn.com/changes/sefaz/2026-10-01-layout-and-validation-rules-update.md) (effective Nov 3, 2026)
- [NFS-e Nacional: vAjusteBC group added in restricted production](https://harbyn.com/changes/nfse-nacional/2026-10-20-criacao-do-grupo-vajustebc.md) (announced Oct 20, 2026)
- [Conta Azul: New client\_id format for new applications](https://harbyn.com/changes/contaazul/2026-10-01-novo-formato-de-client-id-para-novas-aplicacoes.md) (announced Oct 1, 2026)
- [Asaas: Alteração na estrutura de URLs públicas do Asaas](https://harbyn.com/changes/asaas/2026-09-25-alteracao-na-estrutura-de-urls-publicas-do-asaas.md) (effective Sep 28, 2026)

[All upcoming deadlines](https://harbyn.com/deadlines.md)