We recently encountered an issue where moving from one server to another of the same DNN instance had the newer server having problems with the axd files where they displayed either a mime type or 403 error.
I went searching for similar issues and ran across two of the older DNN forum with similar questions/issues:
Their original question/issue was listed as:
i´m running DNN version 07.02.02 and have my site configured to use HTTP and HTTPS.
I use the HTTPS for externel login and HTTP for internal login.
But when i login via HTTPS i always recieve this error:
Failed to load resource: https://website/Telerik.Web.UI.WebResource.axd?compress=1&_TSM_CombinedScripts_=%3b%3bTelerik.Web.UI%2c+Version%3d2014.1.520.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3ade-DE%3a95160b26-aab5-49f8-adb3-b69c7c4a6beb%3a45085116%3a5951aeec%3a9e1572d6%3ac86a4a06%3aaac1aeb7%3bTelerik.Web.UI.Skins%2c+Version%3d2014.1.520.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3ade-DE%3abfceac93-3822-4be2-97dc-feb56413a050%3a929e740d%3a2f734f87%3a26b86afe%3a9e03bb1b%3aa19c4d24
server responded with a status of 403 (Forbidden)
The strange thing is that the app pool user has 'full control' file permission on the DNN folder and still recieves a forbidden error message...
I hope you can help me
In a recent encounter with the same type of issue, different browsers were giving different error responses for the webresource.axd and the Telerik.Web.UI.WebResource.axd files... one was simply giving an Error 403 denied type of response, others were suggesting mime type issue.
In the end, in this occassion, it turned out to be Web Application Firewall rules within Plesk that were causing a problem. The old server had one set of WAF rules, the new server had newer/different Plesk WAF rules and once adjusted, the site ran correctly.