Opening a Workset
If you get an error message suggesting to roll back changes when opening a workset, you can accept the roll back. This means the workset will be rolled back to the last saved version and any intermittent changes are lost. After rollback, you will see the workset in the explorer view as "Not loaded". You need to reload it by either restarting Quadri for Windows or right clicking and selecting "Remove", then right clicking the cloud symbol and selecting "Open workset".
You can also try a manual "Rollback":
Copy the file YourModel.zQuadriModelBackup from the workset directory: Find the Location of a Workset to some other empty directory.
Rename the file to YourModel.zip.
Unpack it
In Quadri for Windows, use "Open single user model" and select type "Quadri Model" and then the YourModel.QuadriModel file.
Check if everything seems OK. Changes you have made since the last successful save will be lost.
If you still get problems opening a workset, often followed by an error message about "Last server operation was interrupted..." and then another message about "Unknown exception", there will normally be a file called "*.InTransaction" or "*.SaveTransactionCtrl" in the directory where the workset is. To find this directory, see: Find the location of a workset. Be sure to have your Windows Explorer setting so it shows "Hidden files", or you will not see these files!
If you delete this file, you should be able to open the workset again.
If this didn't help, check this: Operation failed.