Manifest: Line: 1, column: 1, Syntax error.

[coursewarefactory]

This error happened at once in the browser console after the command npm run start

[lidongyangLeo]

@coursewarefactory
I has same problem.
I don't know why the PUBLIC_URL is doesn't work.
<link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
So I add .env file can fix it.

PUBLIC_URL=http://localhost:3000