Runtime error loading @theia/ai-mcp package

[drochgenius]

I am getting the following runtime error where Theia is trying to load the module @theia/ai-mcp.

Error: Cannot find module '/home/theia/node_modules/.pnpm/@[email protected]/node_modules/@modelcontextprotocol/sdk/dist/cjs/client/stdio'
at createEsmNotFoundErr (node:internal/modules/cjs/loader:1401:15)
at finalizeEsmResolution (node:internal/modules/cjs/loader:1390:15)
at resolveExports (node:internal/modules/cjs/loader:646:14)
at Module._findPath (node:internal/modules/cjs/loader:713:31)
at Module._resolveFilename (node:internal/modules/cjs/loader:1351:27)
at defaultResolveImpl (node:internal/modules/cjs/loader:1021:19)
at resolveForCJSWithHooks (node:internal/modules/cjs/loader:1026:22)

I just updated Theia from version 1.61 to 1.64, I am following community releases.
My NodeJS version is 22.
And I am using PNPM as a package manager, hence the path above.

Looks like the file we're trying to import here does not exist anymore.

[msujew]

Hey @drochgenius,

I believe that's a known issue. The @modelcontextprotocol/sdk package is ESM only and cannot be easily imported from Theia, see #14833. Adopters should use the backend bundling feature to ensure that the package can be loaded correctly (the bundler will transform the package into CJS code).

[sdirix]

@drochgenius This could happen when you are using a webpack configuration generated by an old Theia. To remedy, you could delete/rename your webpack config once so it will be regenerated by the Theia CLI and then add your customizations back in.

[drochgenius]

Thanks @sdirix ,

I am already regenerating the webpack config using the Theia CLI of the save version 1.64, but still have the issue.
I have no customization in webpack, I use the default generated webpack config.
For the moment we had to rollback to 1.61, but let me try a few things and get back to you.

[sdirix]

@drochgenius Just to be sure that we are aligned:

• You are regenerating the webpack.config.js and it includes (and exports) the gen-webpack.node.config.js too?
• The application is started via the theia start command or you run node lib/backend/main.js and not node src-gen/backend/main.js

[drochgenius]

Ah, my problem is that I was running /home/theia/src-gen/backend/main.js instead of /home/theia/lib/backend/main.js

[drochgenius]

Thanks for your help @sdirix