Error running vitest with npm run test:ui: Error: listen EACCES: permission denied ::1:51204

Question

I’m trying to run Vitest with the UI enabled using:

"scripts": {
  "test:ui": "vitest --ui"
}

When I run it with:

npm run test:ui

I get the following error:

Error: listen EACCES: permission denied ::1:51204

Cary Bondoc · Accepted Answer · 2025-09-11 12:44:09Z

1

The issue was that Vitest UI was trying to bind to port 51204 (IPv6 ::1:51204), which Windows was denying permission.

The solution was to explicitly specify a port with the --api option.
Instead of:

"test:ui": "vitest --ui"

use:

"test:ui": "vitest --ui --api 3001"

Now the UI runs properly on port 3001 and displays all test results without errors.

answered Sep 11 at 12:44

Cary Bondoc

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2 Comments

Interesting sir... Filipino pride hehe

Philippines number one :D