CustomErrors mode="Off"
In the interests of adding more situations to this question (because this is where I looked because I was having the exact same problem), here's my answer:
In my case, I cut/pasted the text from the generic error saying in effect if you want to see what's wrong, put
<system.web>
<customErrors mode="Off"/>
</system.web>
So this should have fixed it, but of course not! My problem was that there was a <system.web> node several lines above (before a compilation and authentication node), and a closing tag </system.web> a few lines below that. Once I corrected this, OK, problem solved. What I should have done is copy/pasted only this line:
<customErrors mode="Off"/>
This is from the annals of Stupid Things I Keep Doing Over and Over Again, in the chapter entitled "Copy and Paste Your Way to Destruction".
"Off" is case-sensitive.
Check if the "O" is in uppercase in your web.config file, I've suffered that a few times (as simple as it sounds)
For Sharepoint 2010 applications, you should also edit C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\web.config
and define <customErrors mode="Off" />
This has been driving me insane for the past few days and couldn't get around it but have finally figured it out:
In my machine.config file I had an entry under <system.web>
:
<deployment retail="true" />
This seems to override any other customError settings that you have specified in a web.config file, so setting the above entry to:
<deployment retail="false" />
now means that I can once again see the detailed error messages that I need to.
The machine.config
is located at
32-bit
%windir%\Microsoft.NET\Framework\[version]\config\machine.config
64-bit
%windir%\Microsoft.NET\Framework64\[version]\config\machine.config
Hope that helps someone out there and saves a few hours of hair-pulling.