Problem:
EUM users do not see any EUM metrics from the instrumented application on the Controller.
To troubleshoot, open the EUM Processor's dropped beacon logs (located in EUM/logs/DroppedBeacon.log) which mark all dropped beacons as "invalid."
Next, using Chrome dev tools, under the Network tab, there will be a beacon that is posted as an image (adrum.gif) and the request URL will look similar to: '/eumcollector/adrum.gif?&&&&&&&&&ky=<APP-KEY>'.
As the parameters in this URL are missing, the beacon does not carry any metric data that can be identified by the EUM Server, and it is dropped.
Solution:
This issue appears in applications using Prototype.JS, which interferes with the browser's native JSON.stringify method.
Adrum.js (the Javascript Agent) uses the browser's version of JSON.stringify. When possible, we recommend using a browser's built-in JSON.stringify instead of Prototype's toJSON.
Then check for the window.JSON && window.JSON.stringify and only include the json.org library (via document.createElement('script')…).
To resolve the incompatibilities, include the following just after prototype.js in the browser.
if(window.Prototype) {
delete Object.prototype.toJSON;
delete Array.prototype.toJSON;
delete Hash.prototype.toJSON;
delete String.prototype.toJSON;
}
