Bug Report: Uncaught Error: No such module "wrangler:modules-watch" when running wrangler pages dev on Nitro build

[hpx07]

What versions & operating system are you using?

OS: Windows
Wrangler Version: 4.114.0 (or current)
Node.js Version: v24.14.0
Framework: Nitro (version 3.0.260603-beta), TanStack Start, Vite 8.1.5

Please provide a link to a minimal reproduction

https://github.com/hpx07/nitro-wrangler-bug-repro

Describe the Bug

When running npx wrangler pages dev .output/public on a project built with Nitro (using the cloudflare-module preset), the Workers runtime fails to start due to a missing module error related to wrangler:modules-watch.

Wrangler seems to be attempting to inject development-only "watch" code into a context where it is not supported or where the module is completely absent from the environment, causing a runtime exception.

Steps to Reproduce
Create a project utilizing Nitro with the cloudflare-module preset (e.g., using TanStack Start and @lovable.dev/vite-tanstack-config).
Run the build command (e.g., npm run build or vite build) which generates the .output directory containing .output/server and .output/public.
Run npx wrangler pages dev .output/public.
Observe the local server starting but instantly crashing with a module not found error.

Please provide any relevant error logs

X [ERROR] service core:user:6c8b0a88-a35e-44d4-bb41-924dac6e77da: Uncaught Error: No such module "wrangler:modules-watch".

imported from "pages-shim.js"

X [ERROR] The Workers runtime failed to start. There was likely a problem with the workerd binary or your configuration.

Runtime stderr:
{"timestamp":"1785003887790","level":"error","source":"src/workerd/server/json-logger.c++:127","message":"service
core:user:6c8b0a88-a35e-44d4-bb41-924dac6e77da: Uncaught Error: No such module
"wrangler:modules-watch".\n imported from "pages-shim.js"","context_depth":0}

wrangler_bug_report.md

[workers-devprod]

Note

This is an automated, advisory triage report generated by workers-devprod. It is not an official maintainer response — a maintainer will follow up.

🤖 Automated triage report

Issue Triage: #14845

Summary

wrangler pages dev .output/public crashes with No such module "wrangler:modules-watch" (imported from pages-shim.js) on a Nitro project built with the cloudflare-module preset.

Classification

• Type: Bug
• Component: packages/wrangler (Pages dev) — but root cause appears to be in Nitro's cloudflare-module preset output
• Severity: Medium
• Has Reproduction: Yes (with link: https://github.com/hpx07/nitro-wrangler-bug-repro)
• Quality: Complete

Findings

• Created: not accessible (see note below)
• Author: hpx07 (Preet)
• Version: Wrangler 4.114.0, Node.js v24.14.0, Windows; Nitro 3.0.260603-beta, TanStack Start, Vite 8.1.5
• Labels: not accessible (see note below)
• Comments: not accessible (see note below)

Triage note: context.json is a single-line JSON blob and the tooling truncated the line at 2000 characters. Only the leading portion (author + body) was readable; issue metadata that appears later in the object (labels, comments, created/updated dates, state, state_reason) could not be extracted. The findings below are based on the readable body content.

Analysis

• The two symbols in the error — wrangler:modules-watch and pages-shim.js — do not exist anywhere in the workers-sdk codebase. Both are generated by Nitro's cloudflare-module preset when it emits its server bundle. This strongly indicates the shim/import is authored by Nitro, not by Wrangler.
• The cloudflare-module preset targets the Workers (module-worker) deployment model, whose entry lives in .output/server. The reporter is instead running wrangler pages dev .output/public, which points Pages dev at the static-assets directory. This is a configuration/model mismatch: a module-worker build is being loaded through the Pages dev path, and the Nitro-generated pages-shim.js references a wrangler: virtual module that only resolves in a specific bundling context.
• The report itself is high quality: it includes OS, versions, a minimal reproduction repo, clear steps, and full error logs. If maintainers determine any part is a genuine Wrangler-side resolution bug, the repro is actionable.
• Because the failing module is emitted by Nitro's preset, the most likely correct home for this is the Nitro project (or the framework integration), with a redirect to the appropriate wrangler invocation for a module-worker build.

Recommendation

Status: NEEDS VERIFICATION

Reasoning: The error strings originate from Nitro-generated output (pages-shim.js / wrangler:modules-watch), and the reporter is running wrangler pages dev against a cloudflare-module (Workers) build, which is a model mismatch. A maintainer should confirm whether this is purely a Nitro preset issue (redirect) or whether Wrangler should resolve/error more gracefully here.

Action: Confirm the origin of pages-shim.js and wrangler:modules-watch (Nitro preset output). If confirmed, redirect the reporter to Nitro and to the correct command for a module-worker build. If Wrangler is expected to support this flow, keep open and investigate against the provided repro.

Suggested Labels: (omitted — issue's current labels could not be read; no confidently-existing label to add)

Suggested Comment

Thanks for the detailed report and repro. The error you're hitting — No such module "wrangler:modules-watch" imported from pages-shim.js — comes from the output generated by Nitro's cloudflare-module preset; neither pages-shim.js nor the wrangler:modules-watch virtual module is produced by workers-sdk itself.

A couple of things worth checking:

• The cloudflare-module preset builds a module Worker, whose entry is in .output/server (not .output/public). Running wrangler pages dev .output/public points Pages dev at the static-assets directory, which is a different deployment model. For a module-worker build you generally want to run against the server output / your wrangler.jsonc config rather than pages dev on the public dir.
• If Nitro provides a dedicated Cloudflare Pages preset, that may be the intended target for wrangler pages dev.

Since the failing shim is emitted by Nitro, this is likely best tracked on the Nitro side — could you also open an issue there? If after adjusting the command you still see a resolution error that looks like it's coming from Wrangler, let us know and we'll dig into the repro further.

Structured summary (JSON)

{
  "issueNumber": 14845,
  "title": "wrangler pages dev crashes with No such module \"wrangler:modules-watch\" on Nitro cloudflare-module preset build",
  "githubUrl": "https://github.com/cloudflare/workers-sdk/issues/14845",
  "recommendation": "NEEDS VERIFICATION",
  "difficulty": "medium",
  "reasoning": "The failing symbols (pages-shim.js, wrangler:modules-watch) are emitted by Nitro's cloudflare-module preset, not workers-sdk, and the reporter runs wrangler pages dev against a module-worker build pointed at the static-assets dir. A maintainer should confirm whether this is a Nitro preset issue or a Wrangler resolution gap.",
  "suggestedAction": "Confirm the shim originates from Nitro's cloudflare-module preset; if so, redirect the reporter to Nitro and to the correct command for a module-worker build, otherwise investigate against the provided repro.",
  "hasSuggestedComment": true,
  "suggestedLabels": []
}