[vite] Internal server error:options.devServer. transformWidthEsBuild is not a function…
Vite2.x upgrade Vite3.x error reported this message
In addition to upgrading Vite itself, it is best to upgrade all plugins involved in Vite in package.json devDependencies development dependencies, such as @vitejs/plugin-vue, @vitejs/plugin-legacy, etc.
If not yet solved, try to upgrade the plugins corresponding to Vite involving eslint and so on.