Medusa Admin build fails with ProgressPlugin validation error (webpack conflict)

[gadatos]

Problem

Running:

yarn build

Results in:

ValidationError: Invalid options object. Progress Plugin has been initialized using an options object that does not match the API schema.

options has an unknown property 'name'
options has an unknown property 'color'
options has an unknown property 'reporter'
options has an unknown property 'reporters'
options has an unknown property 'basic'
options has an unknown property 'fancy'
Root Cause

This issue is caused by a version mismatch between webpack and webpackbar.

@medusajs/admin-ui uses webpackbar
webpackbar passes options like:
name, color, reporter, fancy, etc.
Newer versions of webpack (e.g. 5.91.0) do not accept these options in ProgressPlugin

As a result, these options are incorrectly validated by webpack.ProgressPlugin, causing the build to fail.

Why This Happens

@medusajs/admin-ui declares:

"webpack": "^5.84.1"

Because of the caret (^), your package manager may install a newer version, e.g.:

webpack@5.91.0

This introduces a breaking incompatibility with webpackbar.
Solution
Force compatible versions using resolutions (for Yarn v1):

"resolutions": {
"webpack": "5.84.1",
"webpackbar": "5.0.2"
}

[gadatos]

The issue is now resolved.

I'm leaving this here for others — if you run into this error, you can fix it quickly without digging for hours.

The root cause is a webpack version mismatch.

Fix

Add this to your package.json:

"resolutions": {
"webpack": "5.84.1",
"webpackbar": "5.0.2"
}