Those Fenris debug error codes are only able to be seen by opening them on your PC.
This is noted by a blue post in this thread:
Also, it would be helpful if you list any relevant information about your PC (CPU, GPU & Driver, type of connection, and any other relevant crash information)
Follow the instructions below if you want player to player assistance with your crash issue.
Check the support article below
Select Windows / Mac
Select Diablo IV from the drop down menu
Follow the instructions on that page
Then if you want someone to look at the most recent FenrisDebug.txt file, copy and paste the entirety of the .txt file to a new pastebin.
pastebin.com
At the bottom hit Create New Paste
Then share the pastebin link back here
You can share links with ` on each side of the link (before and after).