This is because by default dynatrace is trying to serve js agent on root of site. Some of server configuration doesn’t allow such operation. Good practice is checking path of other js files. For example www.example.com/resources/js. Than in applications settings -> advanced you can set path on which agent will be injected. You should put there /resources/js/. This should solve your issue. If you will than see in devtools that dynatrace is trying to send data and you have 404 errors you should play with beacon path as well.