Solved! Go to Solution.
esri.setRequestPreCallback(function (ioArgs) { if ((ioArgs.url.indexOf("MapServer") > -1) || (ioArgs.url.indexOf("FeatureServer") > -1)) ioArgs.preventCache = true; }
Are you using the proxy code from here?
https://github.com/Esri/resource-proxy
esri.setRequestPreCallback(function (ioArgs) { if ((ioArgs.url.indexOf("MapServer") > -1) || (ioArgs.url.indexOf("FeatureServer") > -1)) ioArgs.preventCache = true; }