Remediation steps for bootbank expansion failure on ESXi Host upgrade from ESXi 8.x to ESX 9.0

Products

• VMware vSphere ESXi
• VMware vSphere ESX 8.x

Issue/Introduction

ESXi 8.x hosts with small bootbanks will undergo "bootbanks expansion" during the upgrade to ESX 9.0 (see "Upgrade on systems with 500 MB bootbanks" section in ESXi System Storage Overview).

In some rare scenarios, system storage plugin might fail during the bootbank expansion process.

If the host:

1. Was in maintenance mode before upgrade, host will boot normally, but host will not be allowed to exit from maintenance mode.
   The following vSphere error will be displayed on the UI:
   "A critical failure was detected during system boot. The host is currently not able to exit maintenance mode and run workloads. Refer to VMware KB 93107 for details."
   In addition, The DCUI screen will show sysAlert depicting the system storage failure and the KB article for remediation. 
   
   
2. Was not in maintenance mode before upgrade, host will PSOD, and the PSOD screen will depict the system storage failure and the KB article for remediation. 

Environment

VMware vSphere ESX 9.0

Resolution

Fresh installation of ESX 9.0 will be required.