Photopia error message

That error appears to indicate a failure in the writing stage of the Blu-ray output process. Using the alternative "ISO image file" output option might be an effective workaround for this situation.

The "Disc Writer" in the "Options" tab of the Blu-ray output window can be set to "ISO image file". Output with that setting enabled and you can save an "ISO" file of your Blu-ray output to your hard drive. You can then right-click on that ISO file and chose the "Burn disc image" (in Windows) to have the operating system (i.e. Windows) do the burning part of the Blu-ray output process. In some cases that's all you need to get a successful Blu-ray disc created.