I had a somewhat frustrating experience today: my Eclipse workspace, which I had spent a great deal of time customizing, was suddenly reverted to the default layout. All Perspectives that I created were gone.

The first thing I did was to look at the log file, which said

Unable to load resource file:/<workspace_path>/.metadata/.plugins/org.eclipse.e4.workbench/workbench.xmi

Alright, a little Google research told me that this was a problem with a detached View that I had opened and then closed via the window X button (Alt+F4 also doesn’t work), instead of the view’s X button. Apparently, there’s a bug in Eclipse that lets it freak out completely, but the solution is rather easy:

In the workbench.xmi file look for a <windows> tag of type basic:TrimmedWindow that contains the View you opened, and then delete the whole tag. If you’re lucky, that’s what’s preventing Eclipse from loading your workbench layout and it should be fixed now.