Error: "block.getRootBlock is not a function" in webpack 5.60.0

Bug report

What is the current behavior?

Running a build with module federation yields the following error:

UnhandledPromiseRejectionWarning: TypeError: block.getRootBlock is not a function
    at getBlockModules (node_modules/webpack/lib/buildChunkGraph.js:219:47)

If the current behavior is a bug, please provide the steps to reproduce.

Unfortunately, my setup is quite “off road”. It mixes Angular, and module federation with @angular-builders/custom-webpack. So it is difficult for me to provide a minimum repro.

However, I narrowed down the error to version 5.58.0 and above. It works fine with version 5.57.1.

What is the expected behavior?

No such error, or a better error message which tells me why getRootBlock is not a function.

Other relevant information: webpack version: 5.58.0 Node.js version: 14.17.0 Operating System: mac Additional tools: module federation, Angular

[hmil]

One package had declared a dependency on a different version of webpack than the main version declared in my project.

So I ended up with something like:

node_modules/webpack
node_modules/foo/node_modules/webpack

I may also have had some dependency yarn linked from somewhere else at the time of the issue.

Anyways, make sure there is only one webpack in your node_modules, especially deeper down in the module tree.

[brandones]

Hi @hmil , can you explain a bit more what you mean by “two different copies of webpack”? Where were the two copies located in the directory structure?

I’m having this same problem. And it’s occurring in my CI build, which would seem to mean that npm is installing things wrong from scratch.