And not getting an error, it's just Fedora can't do anything with the widevine plugin.
The question would be why now all of a sudden are you seeing an issue? The widevine plug in has been required for all *non* DVR content, such as hbo, sho, starz, **AS delivered ** through DishOnline for over 3 months.
If you're seeing an initial prompt for the plugin, that might be triggered by any of the content that's on the main page, and you should still be able to get hulu delivered stuff, as well as anything that isn't DRM protected by WideVine, and your own DVR stuff..
I emphasized "as delivered" because HBO Go / Max Go / Epix Online, those are their own entities and not the same as comes through DishOnline ... Just like DRA (Dish Remote Access) is not the same thing as DO (DishOnline)
Can you check FF and see if it shows the plugin is there, but disabled? If so ... there may be something that could be done, as I had done to the Widevine plugin before, I had taken out its signature, nixed the version in the install file, and then manually installed the plugin. The one unknown, is if you currently have the plugin installed for FF4 before your install updated to 5 ...