How to Perform Full-Outer Join on Two Separate, Filtered/Sliced Tables in DAX?

[strince]

I have an original table named `Error`, and two additional tables (`ErrorBefore` and `ErrorAfter`) derived from the original (e.g. `ErrorAfter = ALLSELECTED('Error')`). I want to compare values from a 'before' version with an 'after' version, with the different version picked by slicer with 'Single select' on. That's working okay. Now I want to perform a full-outer join on the two results, joining on the `Message` column. The image below shows the result I have so far, with a fabricated table at the bottom of what I'm trying to achieve. I've tried using `NATURALLEFTOUTERJOIN` and `GENERATE` but they either don't give the result that I seek. Does anyone know how to perform the join?

PBIX is here.

[strince · Accepted solution]

Someone was able to provide the answer on Stack Overflow.