I guess I am somewhat fortunate here since I do not have any 3rd party modules installed at my sites. However, there are still problems with even the default modules as I have posted about already. Especially the issue with Notifications. That can even be seen here at UNA. 

From what I am seeing, it does look like that some 3rd party apps are not ready for UNA 10 and causing issues. Beta's really shouldn't be installed on LIVE sites that have custom code, 3rd party apps, etc. 

On the other hand, UNA team cannot code their updates based around all 3rd party apps. That would be impossible for them to do. In cases like this, Vendors are left with a choice.. Update your apps to be compatible with UNA 10 and lower versions OR create a separate module specifically for UNA 10 and above. 

I will try my best to help anyone with their site upgrades but, when it comes to sites that have 3rd party apps, there is not much I can do.