filename.replace is not a function error when using @cloudflare/vite-plugin with SSR

[BeiXiao]

Which Cloudflare product(s) does this pertain to?

Vite Plugin

What versions & operating system are you using?

^1.0.8

Please provide a link to a minimal reproduction

No response

Describe the Bug

filename.replace is not a function error when using @cloudflare/vite-plugin with SSR

Environment:

• @cloudflare/vite-plugin (latest)
• @React-router v7
• vite v6

Using SSR build with cloudflare({ viteEnvironment: { name: "ssr" } }),

Error Description:
When configuring @cloudflare/vite-plugin with viteEnvironment: { name: "ssr" } in vite.config.ts, the build fails with the following error:

filename.replace is not a function
   at async ProxyServer.fetch (file:///.../node_modules/.pnpm/miniflare@4.20250417.0/node_modules/miniflare/src/workers/core/proxy.worker.ts:173:11)
The error disappears when removing the viteEnvironment configuration.

Reproduction Steps:

Use the following configuration:

import { cloudflare } from "@cloudflare/vite-plugin";
import { reactRouter } from "@react-router/dev/vite";
import { defineConfig } from "vite";
import macrosPlugin from "vite-plugin-babel-macros";
import tsconfigPaths from "vite-tsconfig-paths";
import { lingui } from "@lingui/vite-plugin";

export default defineConfig(({ isSsrBuild }) => ({
  resolve: {
    alias: {
      "~": "/app",
    },
  },
  plugins: [
    macrosPlugin(),
    cloudflare({ viteEnvironment: { name: "ssr" } }), // Error occurs with this line
    reactRouter(),
    tsconfigPaths(),
    lingui({
      configPath: './lingui.config.ts',
    }),
  ],
  ssr: {
    noExternal: [
      "@udecode/plate-math",
      // ... other packages
    ]},
}));

Run the build with SSR enabled

Expected Behavior:
The build should complete successfully with SSR support enabled through viteEnvironment: { name: "ssr" }.

Actual Behavior:
Build fails with filename.replace is not a function error.

Additional Information:

The error appears to originate from miniflare's proxy worker

The issue is reproducible consistently with this configuration

Removing viteEnvironment configuration makes the error disappear, but we need SSR functionality

Workaround:
Currently, the only workaround is to remove the viteEnvironment configuration, which disables the needed SSR functionality.

Would appreciate any guidance on how to properly configure SSR with this setup. Thank you!

[Amateur0x1]

I encountered the same error.

[jamesopstad]

Removing the ssr.noExternal entry in the Vite config should resolve the issue. Are you able to confirm? It's not necessary as we have resolve.noExternal set to true in the Cloudflare plugin.

I think the cause of the bug is actually in Vite because of the way it merges the legacy ssr config field with the new environments config. This results in this array - ['@udecode/plate-math', true] - and then it tries to call true.replace, which fails. I'll have a look at the Vite code and see if this can be improved.

[FranRom]

Having the same error, removing the noExternal array for my case it's causing a bigger problem...

[jamesopstad]

This should be fixed in vitejs/vite#20077. I'll confirm when that is released.