Update from vCenter 7.0 Update 3 to U3a fails with "Stage path file doesn't exist" or "Package discrepency error, Cannot resume!"

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• The update from vCenter 7.0 Update 3 to vCenter 7.0 Update 3a fails
• Update fails when using ISO and via URL
• The error seen when patching via CLI is:

Command> software-packages stage --url --acceptEulas
[YYYY-MM-DD HH:MM:SS,356] : Discovering updates...
[YYYY-MM-DD HH:MM:SS,534] : UpdateInfo: Using product version 7.0.3.00000 and build 18700403
[YYYY-MM-DD HH:MM:SS,534] : Target VCSA version = 7.0.3.00100
[YYYY-MM-DD HH:MM:SS,000] : Stage path file doesn't exist
[YYYY-MM-DD HH:MM:SS,006] : Staging failed. Retry to resume from the current state. Or please collect the VC support bundle.

• In the vCenter Appliance Management (VAMI) you will see:

"Package discrepency error, Cannot resume!"

Environment

VMware vCenter Server 7.0.x
VMware vCenter Server 7.0.3

Cause

VMware Engineering is aware of this issue, it is currently under investigation.
Please subscribe to the KB article to get notified on changes.

Resolution

This issue is resolved in vCenter Server 7.0 Update 3c.

Workaround:
To work around this issue, follow the steps below:

1. Log in to your vCenter Appliance via SSH.
2. Run following command:

software-packages unstage

3. Start the update process again.

Note: If the default shell was changed to /bin/bash, you can use /bin/appliancesh to enter the Appliance-Shell.
Note: Please ensure you have a working backup before attempting to update your vCenter Appliance.

Fallback/Alternative:
When unstage does not work, the patching.db can be manually reset. However the software-packages command should be preferred in the first place.

Important: Please make sure to have proper backup or offline snapshot before applying the below steps:

The alternative way: 
# service-control --stop applmgmt
# rm -rf /storage/core/software-update/updates/*
# rm -rf /storage/core/software-update/stage/*
# rm -rf /storage/db/patching.db
# mv /storage/core/software-packages/staged-configuration.json /storage/core
# mv /etc/applmgmt/appliance/software_update_state.conf /storage/core
# service-control --start applmgmt