AWS ALB responding with 502s after upgrade to 0.4.0-RC.3

After upgrading to `0.4.0-RC.3` and deploying to AWS, around 10-20% of page requests resulted in a the ALB responding with a 502 http response. This was a single EC2 instance in the target group. We reverted back to `0.2.11` and the service behaved as normal.