Title: VIP Cache Personalization API
Author: WordPress VIP Documentation
Published: October 12, 2021
Last modified: August 5, 2025

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 1. [Changelog](https://docs.wpvip.com/changelog/)
 2. [VIP MU plugins [Production]](https://docs.wpvip.com/changelog/vip-mu-plugins-production/)
 3. VIP Cache Personalization API

# VIP Cache Personalization API

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 12 October 2021

10:59:40 GMT+0000

 [ VIP MU plugins [Production] ](https://docs.wpvip.com/changelog/vip-mu-plugins-production/)

 [ Permalink  ](https://docs.wpvip.com/changelog/vip-mu-plugins-production/vip-cache-personalization-api/)

 * Update `stringify_groups()` to return `string` consistently

[https://github.com/Automattic/vip-go-mu-plugins/pull/2477](https://github.com/Automattic/vip-go-mu-plugins/pull/2477)