There are still dozens of VMs in cloud-vps running Debian Stretch. All of these hosts will need to be deleted and replaced with VMs running either Buster or Bullseye in the next few months. Beginning in May we will begin to shut down Stretch instances.
Please check this page for your projects, and take whatever steps are necessary to move off of Stretch:
https://os-deprecation.toolforge.org/
Don't hesitate to reach out for help on IRC or mailing list if you need help with this migration. You may find Cinder volumes (https://wikitech.wikimedia.org/wiki/Help:Adding_Disk_Space_to_Cloud_VPS_instances#Cinder) especially useful for transferring data between VMs. Note that we do NOT recommend in-place OS upgrades of VMs; it is almost always better to start with a fresh host and transfer workloads over.
Details about the what and why for this process can be found here:
https://wikitech.wikimedia.org/wiki/News/Stretch_deprecation
Here is the remaining deprecation timeline:
May 1, 2022: All active Stretch VMs will be shut down (but not deleted) by WMCS admins.
June 30, 2022: LTS support for Debian Stretch ends, all Stretch VMs will be deleted by WMCS admins