Unfortunately, The Journal 5 doesn’t work with Windows 10. (NOTE: This *only* affects The Journal 5.)
To continue using The Journal after you upgrade to Windows 10, you will need to upgrade to The Journal 7. You can download The Journal 7 from here to install it. The first time you run The Journal 7, it should offer to upgrade you existing entries. Let it.
If you have any questions, please don’t hesitate to ask: firstname.lastname@example.org