I cannot open my ISE 8.x EDIF project with project Navigator 10.1.
This problem occurs when the EDIF source file has not been explicitly set to top-level.
To resolve this issue, follow these steps:
1. In your 8.x Project Navigator, open your design.
2. Right-click the EDIF source and select "Set as Top Module."
3. Close the project and open it in Project Navigator 10.1.
This problem has been fixed in the latest 10.1 Service Pack available at:
The first service pack containing the fix is 10.1 Service Pack 2.