[prerender-spa-plugin] Unable to prerender all routes! when upgrade webpack to v5+

ERROR in [prerender-spa-plugin] Unable to prerender all routes! this happened in webpack5, but work well in webpack4

node env: v12.18.2

error messages comes out with deeply debug;

webpack5 breaked here because of this:

https://webpack.js.org/blog/2020-10-10-webpack-5-release/#filesystems

Filesystems Next to compiler.inputFileSystem and compiler.outputFileSystem there is a new compiler.intermediateFileSystem for all fs actions that are not considered as input or output, like writing records, cache or profiling output.

The filesystems have now the fs interface and do no longer demand additional methods like join or mkdirp. But if they have methods like join or dirname they are used.

code update here to be compatible with both webpack4/5

  // From https://github.com/ahmadnassri/mkdirp-promise/blob/master/lib/index.js
  const mkdirp = function (dir, opts) {
    return new Promise((resolve, reject) => {
      console.log('\ndir', dir, opts, '\n');
      try {
        compilerFS.mkdirp(dir, opts, (err, made) => err === null ? resolve(made) : reject(err))
      } catch(e) {
        compilerFS.mkdir(dir, opts, (err, made) => err === null ? resolve(made) : reject(err))
      }
    })
  }

[dreysolano]

For anyone interested, I forked the main project and created the following package which has the fix noted above for Webpack 5, along with up-to-date dependencies. Hopefully this can be PRed back into the main project repo if/when @chrisvfritz and team start supporting again.

https://www.npmjs.com/package/@dreysolano/prerender-spa-plugin

[dreysolano]

Nice find all. One caveat is that the above will not work for nested routes such as /pages/about-us if the /pages dir does not already exist. The solution here is to pass {recursive: true} in the opts param. This solved the issue for me:

compilerFS.mkdir(dir, {...opts, recursive: true}, (err, made) => err === null ? resolve(made) : reject(err))

@chrisvfritz - any chance that this project will be supported again soon? I’m sure a number of us in the community would be happy to lend a hand!