Webpack has been initialised using a configuration object that does not match the API schema.

[22Viig]

Following the readme guide and launching lektor with lektor server -f webpack it returns the following error:

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema.
 - configuration.resolve has an unknown property 'modulesDirectories'. These properties are valid:
   object { alias?, aliasFields?, cachePredicate?, descriptionFiles?, enforceExtension?, enforceModuleExtension?, extensions?, fileSystem?, mainFields?, mainFiles?, moduleExtensions?, modules?, plugins?, resolver?, symlinks?, unsafeCache?, useSyncFileSystemCalls? }
 - configuration.resolve.extensions[0] should not be empty.

[StefanYohansson]

seems like readme example was wrote before webpack 2.x. So npm install --save-dev command install latest webpack version and webpack 2.x has a different api. You need to change:

resolve: {
  modulesDirectories: [...]
}

to something like this:

resolve: {
  modules: [...]
}

(maybe this solution leads to another problem) I think the best way is to fix the right version on npm install command.

[obestwalter]

As @StefanYohansson mentioned already this is a web pack two issue and can be resolved for the time being with version pinning. See: https://github.com/lektor/lektor-webpack-support/issues/14