Pivotal Cloud Foundry Ops Manager 1.11.1
Starting 1.11.0, Ops Manager has updated the VM catalog on AWS. For customers who deployed Diego cells with Ops Manager 1.10, the Diego VMs defaulted to r3 that had 32 GB of RAM. After upgrading Diego, VMs default to m4 that has only 16 GB of RAM and this results in an insufficient memory issue.
Select the VM type that has a minimum of 32 GB of RAM manually on the Resource Config Page.
This issue is documented in the Known Issues section for Ops Manager 1.11 Release Notes.