I am having the same error in my asp.net page. Please can anyone help me diagnose what sort of problem could cause this? No errors seem to raised in the code, although I have noticed that the message 'compilation error' flashes up briefly in the browser tab title, when I first start the app.  I also have the CKeditor on the same page, and if I remove it the error goes away. Could there be some incompatibility?

 

I have also disabled the friendly error messages as suggested before, but there is no difference in the message displayed.

 

The error only occurs when I upload a second file (not as part of a multiple selection, but by clicking the uploader button a second time).

 

Suggestions or workarounds welcome!

 

Many thanks