[BUG] R2/KV Incrememental cache doesn't work when prerendering a large number of routes

[maamokun]

Describe the bug

When I deploy an app using OpenNext Cloudflare that has uses ISR with a large number of prerendered routes (in my case around 300) the builds always get stuck at the "populating (R2/KV) incremental cache..."stage until the builds eventually time out. The same app works as expected when using the Static Assets caching method, however I cannot revalidate pages using that method.

Steps to reproduce

• Create a page in a Next.js app that uses ISR, with a large number of prerendered routes
• Set up either R2 or KV incremental caching
• Deploy the app using Workers Builds

Expected behavior

App deploying successfully with routes prerendered

@opennextjs/cloudflare version

1.0.0-beta.4

Wrangler version

4.14.1

next info output

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Pro
  Available memory (MB): 65464
  Available CPU cores: 16
Binaries:
  Node: 22.15.0
  npm: 10.9.2
  Yarn: 1.22.22
  pnpm: 9.4.0
Relevant Packages:
  next: 15.3.1 // Latest available version is detected (15.3.1).
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: N/A

Additional context

No response

[vicb]

Batch KV population will be enabled in the next release.
We will work on batch R2 population later.

[jordanthornquest]

@vicb - Here's the info you requested for my feedback on R2 cache population speed:

• Deployment takes about 6 minutes when caching 123 assets in R2.
• 344 files in the project's src/ directory.
• 2.9mb gzipped.
• Deployed locally via opennextjs-cloudflare build && opennextjs-cloudflare deploy.

open-next.config.ts:

import { defineCloudflareConfig } from "@opennextjs/cloudflare";
import r2IncrementalCache from "@opennextjs/cloudflare/overrides/incremental-cache/r2-incremental-cache";
import { withRegionalCache } from "@opennextjs/cloudflare/overrides/incremental-cache/regional-cache";
import doQueue from "@opennextjs/cloudflare/overrides/queue/do-queue";

export default defineCloudflareConfig({
  enableCacheInterception: true,
  incrementalCache: withRegionalCache(r2IncrementalCache, {
    mode: "short-lived",
  }),
  queue: doQueue,
});

Let me know if there's anything else I can provide.

[2-fly-4-ai]

I also don't understand this. It takes forever. For any site of a reasonable size it will cause your builds to fail. Should we just not use it? Why does it have to rebuild the whole cache from scratch everytime?

[maamokun]

As this causes the build to hang until it times out (therefore costing you the maximum amount of build minutes) is using R2 to be avoided for large sites? I've used at least an hour of build minutes on failed builds because of this, and while the generous plan limits mean I don't mind, I hope this is fixed!

[wldbest]

We are currently looking into caching 40,000 static pages, but based on the current solution, it seems that it is not yet ready for large-scale use of the pre-render function.

At the very least, I think the resume function is essential when deploying.

It would also be nice if we could pre-generate all the caching files to be synced to the local computer. This would allow us to upload/sync through a separate process without having to worry about resume and other issues.