How do I solve the error 'Video filter missing: AE.ADBE BlackmagicRawPremiereSourceEffect' ?

This error message means that you opened a Premiere Pro project that was using Blackmagic's Adobe plugins for Blackmagic RAW, and now you don't have that plugin installed anymore so it cannot find the Source Settings effect linked to each .BRAW in your Premiere Pro project.
The simplest to fix this issue to install again Blackmagic Design's Adobe plugin. If you're now using BRAW Studio you will have a missing Source Settings filter in the Master tab of your .BRAW and won't be able to retrieve your Source Settings color grade.
Go back to BRAW Studio User Guide