Saw this and thought I'd clarify my experience, especially when using a clustered Mid-Tier writing to the same Data Server on Compute.
By default prostgres is configured on compute with 256 max connections, upping this to 512 will resolve the issue when starting the JVMs.
Note, when you get stuck on stage 11 (Starting Web Application Server), make the change in WIP Data server and restart WIP Data Server. stop any JVMs that is running on the server you are configuring and hit retry.
Restarting is fine, but the problem will not be resolved especially when you have scheduled restarts of JVMs.