Was in the process of updating the mods in my instance of Sky Factory 3 when I got this crash: https://pastebin.com/Kj7u0uWp

At this point, I had no way to sift through and find the mods responsible, so I removed the pack and started going through and keeping track of version numbers of the mods I updated. While I as in the middle of this, I got an unrelated crash and research indicated to update the "Surge" mod (an optimization mod) to fix. Foamfix caught another issue during loading and since it was the Anarchy version, I disabled it. After another launch, I got the same crash as above.

Looking through the trace, I saw Surge mentioned with MoarSigns being crashed. Disabled Surge and now SF3 loads just fine. For the moment, I'm going to leave Surge disabled.

Related versions:
MoarSigns v1.10.2-4.2.2.8
Surge v1.10.2-1.1.0.70