Sometimes when you’re kicking around on a SharePoint site you encounter something strange or you get an error. On some sites, for example a public web site, the error may not contain the correlation ID — SharePoint’s unique identifier for your request — that comes standard on error pages in SharePoint 2010 and SharePoint 2013. At some point the site’s architect decided outputting this to the user wasn’t something they wanted and the developers removed it from the error page. As in, the “error page” is “friendly” and contains no “useful” diagnostic information.
Not having the correlation ID makes troubleshooting difficult, because the ID helps enormously with tracking down exceptions and makes following the flow of a request within the ULS logs (relatively) simple.
[Got a correlation ID and not sure how to find the log entries? Check out An even better way to get the real SharePoint error from the ULS logs featuring the always excellent Merge-SPLogFile SharePoint PowerShell cmdlet)]
Thankfully, SharePoint tells you the correlation ID on every request to the site, even if there weren’t any errors. Finally reading ULS logs becomes a realistic hobby.
So where is the correlation ID? It’s in the SPRequestGuid HTTP response header (MSDN: SPResponseGuid). If you’re using a tool like Fiddler, it captures all the headers in its log. This is useful if you or your testers are doing lots of tests and you want to review a specific test in the logs later.
If you don’t use Fiddler, never fear. Chrome, Firefox, and probably IE can show you the headers in their “developer tools” (on Windows, other browsers and platforms may too).
Correlation IDs were introduced in SharePoint 2010 so this will only work in SharePoint 2010 or newer farms including SharePoint Online (Office 365)! You may wonder how useful it is to have the correlation ID in SPO (or any hosted SharePoint solution) since you don’t have physical access to the ULS logs, but consider providing the correlation ID to Microsoft Support when working with them so you can help them narrow down your request from the hojillion requests hitting their servers. Actually, same thing if you’re not the farm administrator. Putting the correlation ID in your email to your SharePoint administrators for them it’s like winning the lottery. You’ll totally make their day.
Let’s see it in action. In Chrome it looks something like this for SharePoint 2010: