I also tried to upgrade through SNN 2.7 by first going to service_news and upgrading content first to version 2.7. However, I get the same error upon trying to upgrade to 2.8b1.
I also tried to upgrade through SNN 2.7 by first going to service_news and upgrading content first to version 2.7. However, I get the same error upon trying to upgrade to 2.8b1.