As part of our 1.0 release, we need to support css-loader@^3.0.0 which was added to create-react-app in #7876.

Across various issues (#231, #242, #243), the new css-loader configuration format (a switch from a boolean to options for lessOptions) has caused errors during the run and build process of customize-cra.

With version 1.0, we have introduced a fix for this, although it is a breaking change, and will require maintainers to alter their customizers configurations.

In particular, configuration options for the addLessLoader customizer will now be nested in a lessOptions object, as so:

Before:

addLessLoader({
  javascriptEnabled: true,
  modifyVars: { '@primary-color': '#A80000' },
}),

Now:

addLessLoader({
  lessOptions: {
    javascriptEnabled: true,
    modifyVars: { '@primary-color': '#A80000' },
  },
}),

For additional information, please see the revised docs.

If you run into issues migrating to the 1.0 release, please report the issue, and fall-back to the 0.9.1 release until I can diagnose and help you resolve your issue.