I could reproduce this also locally with my current branches, it happens sporadically after running lots of tests, probably a race condition.
The 2 times I have seen this, it seems related to the following line appearing before (it didn't show up in the logs beforehand):
""" <0024> sccp_scoc.c:1878 0: SCCP(rctx=0) Received CO:RELRE: Cannot find connection for local reference 4203660 """