@viktor_g Yea, I fixed that error with a patch here...
https://forum.netgate.com/topic/169869/there-were-errors-loading-rules-solved-and-patched/7
The problem was the continuous emails every 20 to 30 seconds.
The fix for me was to uninstall mailreports, disable SMTP notifications under "System -> Advanced -> Notifications" and reboot.
Uninstalling and disabling wasn't enough, the emails kept going, a reboot is required following the disable and uninstall.
After the reboot the emails stopped. I then enabled SMTP notifications and a couple emails came through but not continuously.
Later I then reinstalled mailreports and everything seemed to be normal and continues to look normal as I'm not getting blasted with the same error in my emails.
Keep in mind that prior to disabling and uninstalling I had already done a couple reboots.
First reboot was after the upgrade
Second reboot was to try to get the emails to stop
Third reboot was after disabling SMTP notifications and removing mailreports.
I wanted to at least post it on the forums that this had happened in case others ended up with the same issue as it could be a potential upgrade bug, but time will tell and now if others have the same problem they know what I did to get the emails to stop and return to normal.