vCSA 7 Update Failed - "Error in method invocation [Errno 2] No such file or directory" and "Update installation is in progress"

Well, that didn't go as planned...

I had a VMWare vCSA that was running version 7.0 GA that was in need of an update.  The pre-update check ran successfully, the update was staged (5GB) and I began the installation.  

After an hour, the progress was still 0%, I clicked "Cancel Installation" and received the following error:

Error in method invocation [Errno 2] No such file or directory

I then performed a graceful restart of the appliance and received the following from the VAMI when logging in using root creds:

"Update installation is in progress"

To resolve this issue I SSH'd into the appliance and performed the following:

1. Create a copy of the software_update_state.conf file.  The file is located in the /etc/applmgmt/appliance/ directory

cp software_update_state.conf software_update_state_backup.conf

2. Stop the applmgmt service.

service-control --stop applmgmt

3. Delete the software_update_state.conf file.

rm software_update_state.conf

4. Confirm the applmgmt service starts successfully.

service-control --start applmgmt

I was then able to successfully log into the VAMI and complete the install. 

5. I un-staged the update. (Neat, reboot not required)

6. This time, I selected "Stage and Install"

7. The update installed successfully and the vCSA is now running the latest release. 

This appears to be an issue when a vCSA update is unsuccessful.  Deleting the original software update state config file and having the vCSA create a fresh one looks to resolve the issue.