client-side

I catch a Exception, When I download Vaadin 16 Business Starter and copy /target/index.ts(html) to fronted dir. Then run command :

mvn jetty:run-exploded -Dvaadin.productionMode

Open browser: 127.0.0.1:8080

HTTP ERROR 500
Problem accessing /. Reason:

    Server Error

The IDEA shows Error is

java.io.IOException: Failed to load content of 
'D:\broderick\d