I am having a very similar issue as is mentioned here: https://community.esri.com/message/399585. I've added in Print dijit and PrintTemplate task and get a print button. However, when I click it, it changes from Print to Printing, runs for a bit, then changes back to Print. When I check the Firefox developer tools, I get this error:

I've added in a proxy on my server and gone through the steps to enable CORS mentioned at enable cross-origin resource sharing. I'm still getting the error.
At this point, I'm not sure if it is an issue in my code, or that I need to place the proxy on my local machine, where I'm building. I can't turn on IIS on my local machine, as our IT folks don't allow it.
Here's the code I added in for printing and the proxy:
esriConfig.defaults.io.proxyUrl = "http://myURL/DotNet/proxy.ashx",
esriConfig.defaults.io.alwaysUseProxy = false;
//Create Printer Layouts Array
var myLayouts = [{
"name": "Print_Landscape",
"label": "Letter (Landscape Orientation)",
"format": "pdf"
}, {
"name": "Print_Portrait",
"label": "Letter (Portrait Orientation)",
"format": "pdf"
}];
//Create Print Templates
var myTemplates = [];
dojo.forEach(myLayouts, function (lo) {
var printTemp = new PrintTemplate();
printTemp.layout = lo.name;
printTemp.label = lo.label;
printTemp.format = lo.format
myTemplates.push(printTemp);
});
And this portion after creation of my map:
//Add Print Widget
var PrintWidget = new Print({
map: mapMain,
url: "https://myURL/rest/services/CustomPrint/GPServer/Export%20Web%20Map",
templates: myTemplates
}, "PrintWidg");
PrintWidget.startup();
Any help/guidance would be much appreciated! Thank you in advance!
Ashley