Next.js ISR on OpenNext + Workers KV: why the cache never expires and how to cap it

Key points

• The author found that OpenNext's KV incremental cache calls kv.put() without an expirationTtl (the source still carries a TODO about KV TTL), so a page's revalidate value does not make the KV entry expire.
• Each opennextjs-cloudflare deploy runs populateCache, which bulk-puts every prerendered page's HTML and RSC payload under the new Build ID prefix. Old prefixes are never read again but stay stored; after dozens of deploys his namespace reached 24 GB, and the billing period showed 3.59 GB-month of storage.
• His fix: move to a new namespace and delete the old one, wrap the cache so every put carries expirationTtl = min(7 days, max(60 s, 2 × revalidate)), and patch the bulk-put step to add expiration_ttl 604800.
• Official KV docs (rechecked 2026-10-14): Workers Paid includes 1 GB stored, then $0.50 per GB-month; each key in a REST bulk write counts as one write; expirationTtl must be at least 60 seconds, and expired keys stop counting toward storage.

Original sources

1. Published2026-10-13

   Next.js ISR on OpenNext + Workers KV: why the cache never expires and how to cap it

   Open original source

   Meathill traces a KV storage overage on his own site to OpenNext's KV incremental cache writing keys without a TTL and keeping every deploy's build-prefixed snapshot, then shows how he rebuilt the cache lifecycle.

2. 2026-10-13

   The author shares the article on 𝕏 and lists his 2026 bill surprises by month: image transformations (July), containers (August), self-inflicted prefetch traffic (September) and the KV cache (October).

   Read on 𝕏

   Meathill

   @meathill1 · Original 𝕏 post

   作为Cloudflare资深用户，我的独立开发生涯不断被账单背刺： - 七月：图片转换被坑 - 八月：容器使用被坑 - 九月：prefetch DDOS 自己 - 十月：KV 缓存爆炸 这次分享的，就是我本以为开源框架应该已经做好了，但实际上 // TODO 多年的一个缓存陷阱： https://t.co/NjRzSo510W

   2026-10-13 09:20:30 UTC