Clean MS Project Local Cache

Never open MS Project files directly from your cache, you should always open from the saved location (typically the MS Project Server) to get the most recent version.  You should periodically clean your cache, to prevent any issues opening or closing MS Project files from the server.

1. Within MS Project, go to the File menu item on the ribbon and Click on options | Save | Cleanup cache...
2. Look at both project filters (in the middle of the dialog, projects checked out to you and projects not checked out to you) and highlight the project you wish to remove from your cache and click the "Remove From Cache" button

To add the Cleanup Cache to your quick menu within MS Project (will add an icon to the MS Project ribbon toolbar to go directly to the cleanup cache:

1. Go to File | Options | Quick Access Toolbar |
2. Select "All Commands" in the "Choose Commands" combo box
3. Select the "Cleanup Cache" command and add it to the Quick Access Toolbar.
4. The Icon will show up on the toolbar next to the undo/redo buttons.

In some extreme cases, when files do not clean from the cache as above you may need to navigate to the folder where the cache resides on your local drive and delete files.  Here are the steps to accomplish that:

1. Open MS Project, go to menu item Tools -> Local Project Cache -> Cache Settings
2. Copy the Path given in the Cache Location field
3. Close MS Project (you have to close MS Project before doing the next steps to release locked cache folders)
4. Open Windows Explorer and browse to the folder given in the Cache Location, or alternatively you can Paste the path copied in step-2
5. Delete all subfolders and files under the Cache Location; don’t delete the “Cache” folder itself
6. Open MS Project again and check the lookup values.  The problem should be fixed.