Do you have some other code that ends the response or adds headers upon a request? This error is thrown when you try to add a header after the request has been ended or you try to duplicate the header.
I set a project that uses Sitefinity 5.4.4040
. Uploaded several images and the log is still empty. Set Elmah an still the same here.
Have you set AccessControlAllowOrigin property in SecurityConfig? The only header added to this method is when AccessControlAllowOrigin is set
If you install a new project and upload a single image do you have something in sitefinity's log?
Can you check if there is a difference if you use Sitefinity's project manager to browse the website and if yu host the website in IIS.
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