One of the first things you will realize when working on your custom master page is that when you make a mistake, SharePoint’s default error messages are rather unhelpful. As mentioned earlier, if you omit one of the required content placeholders and browse a site that uses your master page,SharePoint will reply with simply “An unexpected error has occurred.” SharePoint can actually return descriptive error messages, but they are turned off by default for security reasons. If you are working in a development environment,
though, it’s imperative to enable these full error messages.
Here are the steps for turning on the full error messages:
1. Log in to the physical SharePoint Server machine and navigate to the directory that holds your SharePoint website. It will most likely be located at C:\inetpub\wwwroot\wss\VirtualDirectories\ and will be in a subdirectory with the port number of your SharePoint site. If you have trouble finding it, you can open IIS7 and in the Sites folder, right-click your SharePoint site, and then select Explore. This will take you directly to the directory that holds your SharePoint website.
2. Locate the fi le named web.config and open it for editing in Notepad.
3. Press Ctrl+F and find the line of code that contains the word “callstack.” You will find a line that looks like this:
<SafeMode MaxControls=”200” CallStack=”false” DirectFileDependencies=”10”
TotalFileDependencies=”50” AllowPageLevelTrace=”false”>
Change both the CallStack and AllowPageLevelTrace attributes from false to true.
4. Press Ctrl+F again and this time search for the word “errors.” You will fi nd a line that looks
like this:
<customErrors mode=”On” />
Change the mode from On to Off. This tells IIS not to show its customary basic error messages and to instead display the raw detailed error messages.
5. Save and close web.config. Note that this change will cause IIS to restart the web application in which your SharePoint site resides. Be careful when making edits to this file in production or shared development environments.
With these changes in place, browsing a page with an error will now reveal the complete error message.