Some time ago I was doing maintenance work on some classic ASP pages and couldn’t get detailed error reports sent back to the browser. Using Internet Explorer I disabled “Show friendly HTTP error messages” but still received the generic HTTP 500 type error messages from IIS 7.0 running under Windows Server 2008. The same also occurred under FireFox. The modifications I was making to the ASP pages were fairly limited so I gave up on trying to get it to work and ending up sticking with examining the IIS logs on the server for debugging information.
Today I started work on maintaining some more complex ASP pages developed by someone else under Vista x64 and IIS 7 and encountered the same problem. I also noticed Vista locks the IIS log files while the web server is running which further added to my determination to get ASP errors including line numbers back to the browser. It appears setting “Send Errors To Browser” in “Debugging Properties” for the ASP properties doesn’t work at a virtual directory level, it only works when enabled at the root level for the entire site. Enabling it at the higher level got back the detailed error reports as per the default bahaviour of IIS 6.