[BUG] trailingSlash breaks Next.js image optimization

[cdl]

Describe the bug

When trailingSlash is enabled in next.config.js, requests to the Next optimization route (/_next/image) fail with a 500 Internal Server Error using opennextjs-cloudflare build && opennextjs-cloudflare preview (as well as when deployed on Workers). Below is a stack trace with some relevant snippets.

First Request

✘ [ERROR]  ⨯ EvalError: Code generation from strings disallowed for this context

      at [object Object]
      at deprecate.wrapfunction [as function]
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:279:729)
      at 228
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:282:16131)
      at __nccwpck_require__2
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:292:36599)
      at null.<anonymous>
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:292:36750)
      at .open-next/server-functions/default/node_modules/next/dist/compiled/send/index.js
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:292:36792)
      at null.<anonymous>
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:2:679)
      at .open-next/server-functions/default/node_modules/next/dist/server/serve-static.js
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:292:37303)
      at null.<anonymous>
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:2:679)
      at
  .open-next/server-functions/default/node_modules/next/dist/server/image-optimizer.js
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:293:105209)


[wrangler:info] GET /_next/image/ 500 Internal Server Error (40ms)

Successive Requests

✘ [ERROR]  ⨯ TypeError: ImageOptimizerCache is not a constructor

      at NextNodeServer.handleNextImageRequest
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:297:15836)
      at Server3.normalizeAndAttachMetadata
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:23:28821)
      at NextNodeServer.handleRequestImpl
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:24:18934)
      at async processRequest
  (file:///Users/colby/code/toolbox/.open-next/server-functions/default/handler.mjs:313:48763)
      at null.<anonymous> (async
  file:///Users/colby/code/toolbox/.wrangler/tmp/dev-n0E6Fh/worker.js:3323:5)
      at null.<anonymous> (async
  file:///Users/colby/code/toolbox/.wrangler/tmp/dev-n0E6Fh/worker.js:3096:16)


[wrangler:info] GET /_next/image/ 500 Internal Server Error (5ms)

This appears to happen for any image regardless of format, size, name, or other properties. Let me know if you need any more info to help diagnose, debug, or reproduce this.

Steps to reproduce

1. Create a new next application (eg: npx create-next-app image-testing)
2. Install @opennextjs/cloudflare, wrangler dev dependencies.
3. Add "preview": "opennextjs-cloudflare build && opennextjs-cloudflare preview" script to package.json.
4. Within the pages router, use the <Image> component with an imported image.
5. Run npm run preview and visit the page.

Expected behavior

Image is rendered the same as it is within next dev, returning a 200 status code.

@opennextjs/cloudflare version

1.8.0

Wrangler version

4.34.0

next info output

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:30 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6020
  Available memory (MB): 32768
  Available CPU cores: 12
Binaries:
  Node: 22.15.0
  npm: 11.4.1
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.5.2 // Latest available version is detected (15.5.2).
  eslint-config-next: 15.5.2
  react: 19.1.1
  react-dom: 19.1.1
  typescript: 5.9.2
Next.js Config:
  output: N/A

Additional context

No response

[sommeeeer]

Thanks for the issue @cdl

Could you try building with this

[cdl]

Wow, just want to thank you for such a fast fix!! Went to review this AM after your ping and see it's already been taken care of. Can confirm I'm no longer seeing this on 1.8.1! 🙏

[vicb]

I can only second that, @sommeeeer is amazingly fast to reply to / fix issues and help the community on Discord 🙏