IIS 7 errors are not being displayed

Hi I use IIS 7 locally and on the Server, I'm able to run all ASP.NET pages with no problems.

Only when a page create an exceptions, instead of visualize any error message and details.

I get only an IE windows saying

Do you want open or download file .... 

I already tried, in web.config customerror="off"开发者_运维知识库 and in IIS / ASP / Debugging > send error to browser but just does not work.

Any Ideas what I'm doing wrong? Thanks

iis 7 unable send error message to browser such as asp classic and iis old version u can user error handler in cs file easily