PASW 2.3.5 release bumps Diego to version 2.20.0. Refer to this link for more information: https://docs.pivotal.io/pivotalcf/2-3/pcf-release-notes/windows-rn.html#2.3.5
Diego in PAS 2.3.4 is version 2.18.0. Refer to this link for more information: https://docs.pivotal.io/pivotalcf/2-3/pcf-release-notes/runtime-rn.html#2.3.4
IST 2.3.5 release bumps Diego to version 2.20.0. Refer to this link for more information: https://docs.pivotal.io/pivotalcf/2-3/pcf-release-notes/segment-rn.html#2.3.5
PASW 2012R2 2.3.4 release bumps Diego to version 2.20.0. Refer to this link for more information: https://docs.pivotal.io/pivotalcf/2-3/pcf-release-notes/windows-2012r2-rn.html#2.3.4
When you upgrade PASW to version 2.3.5 or greater, and the PAS tile stays at a version 2.3.4 or less, the Diego releases become out of sync between the PASW tile and the PAS tile.
When you upgrade: PASW to version 2.3.5 or greater, PASW 2012R2 to version 2.3.4 or greater, or to IST version 2.3.5 or greater, and the PAS tile stays at a version 2.3.4 or less, the Diego releases become out of sync between the PASW tile and the PAS tile.
There was a new Bulletin Board System (BBS) endpoint added in Diego 2.20.0 that was not present in v2.18.0, causing Diego to break. For more information, refer to this link: https://github.com/cloudfoundry/diego-release/releases/tag/v2.20.0.
Note: The stemcell-version would have nothing to do with this issue.
The resolution to this issue is to upgrade the PAS tile, at a minimum, to version 2.3.5.
Note: For those using older versions of the PASW, PASW 2012R2, and IST tiles, they are forward compatible with newer BBS servers in newer PAS tiles. So, if you were to upgrade the PAS tile first to v2.3.5 and the PASW tile stays at v2.3.4, PASW 2012R2 stays at 2.3.3, or IST stays at 2.3.4, you will not encounter this issue.