extension_unsupported

A file or import names an extension that is not allowed here.

A file, or the file an import names, has an extension that is not allowed in this place. Modules are .js (and .ts in TypeScript projects only); assets are lowercase .png, .jpg, .jpeg, .webp, .mp3, .ogg or .wav.

Why it happens

• The extension is not on the list at all (.json, .svg, .mjs, .jsx), or it is in upper case (.PNG).

• .tsx, .mts, .cts and .d.ts files are never accepted.

• A JavaScript project (its entry ends in .js) contains or imports a .ts file.

• An archive contains a .ts file; archives hold only emitted .js.

Wrong

import logo from "./logo.svg";
import levels from "./levels.json";

Right

import logo from "./logo.png";
import { levels } from "./levels.js";

See also

• Assets

• Project structure & imports