I too have dreaded this error – it means nothing to me and just pisses me off especially when developing webparts.

You can remove this by opening the web.config,

Search for <customErrors mode=On /> and change it to <customErrors mode=Off />

To see the call stack and trace information. Find

<SafeMode MaxControls=200CallStack=falseDirectFileDependencies=10TotalFileDependencies=50AllowPageLevelTrace=false>

and change the value of “CallStack” to true.

<SafeMode MaxControls=200CallStack=trueDirectFileDependencies=10TotalFileDependencies=50AllowPageLevelTrace=true>

Finally, don’t forget the set debug=”true” in the web.config or it won’t matter whether you put the assembly in GAC or not without it the breakpoints will turn all nice and red, but it won’t stop anywhere. If you want to enable generation of debug symbols for just in time compilation Find

<compilation batch=false debug=false>

and change it to

<compilation batch=false debug=true>.

Although none of these are appropriate for a production environment, but they all make development much easier.

-Ibrahim Sukari