Upgrading to Windows stemcell v2019.85 fails due to drive space on root disk (C: drive)

Products

• VMware Tanzu Platform
• VMware vSphere Kubernetes Service
• VMware Tanzu Application Service
• Concourse for VMware Tanzu

Issue/Introduction

A user attempts to upgrade a Windows stemcell to v2019.85 and the Apply Changes fails with below error:

There is not enough space on the disk.
Failed pulling C:/var/vcap/packages/windows2019fs image

Cause

As of the March 2025 Windows Update, the C:\Windows\SystemTemp directory is used by default as the temporary directory for system users. This breaks BOSH lifecycle scripts that record large amounts of data in temporary directories because it is on the root disk instead of the expected ephemeral disk.

• https://github.com/cloudfoundry/bosh-agent/commit/bd3673037ff3dcc88b1c47eb423e78e48a76a3b1#:~:text=As%20of%20the,expected%20ephemeral%20disk.

Resolution

Download and upgrade to Windows stemcell v2019.86. 

• Known Issue Fix: BOSH lifecycle scripts no longer use the root disk for temporary directories. They will now use the (configurable) ephemeral disk.

Additional Information

• This issue affects the root disk/volume of a VM and does not impact ephemeral or persistent disks.