_tshoot-err-upgrade-all-fails.html.md.erb

If the [`upgrade-all-service-instances`](#upgrade-all) errand fails,
look at the errand output in the Ops Manager log.

If an instance fails to upgrade, debug and fix it before running the errand again
to prevent any failure issues from spreading to other on-demand instances.

Once the Ops Manager log no longer lists the deployment as `failing`,
[re-run the errand](#upgrade-all) to upgrade the rest of the instances.