Couldn't load a xcode project because it is already opened from another project or workspace

I have a project that has one target dependency. The target dependency is dependent on a framework called Three20.

The dependency tree looks like this.

myProject
   -> myCustomFramework
         -> Three20

When I tried to build and run I get the following error message.

Workspace Integrity Couldn't load Three20.xcodeproj because it is already opened from another projet or workspace.

I have only one project open. Any suggestions on why I am getting this message?

Solution 1:

I had the exact same problem. Quitting the xcode completely and opening it up again worked.

Solution 2:

Quitting Xcode alone didn't work for me. What I did was:

1. File->Close Workspace/Project on every open workspace.
2. Xcode->Quit
3. Open Xcode again and open troublesome workspace