Backing up ESXi host configuration fails with "Internal error".

Products

• VMware vSphere ESXi

Issue/Introduction

• The backup command fails with "Internal error".
  vim-cmd hostsvc/firmware/backup_config
  (vmodl.fault.SystemError) {
     faultCause = (vmodl.MethodFault) null,
     faultMessage = <unset>,
     reason = "Internal error"
     msg = "Received SOAP response fault from [***]: backupConfiguration
  A general system error occurred: Internal error"
  }
• The hostd log shows "The ramdisk 'tmp' is full".
  hostd.log
  yyyy-mm-ddThh:mm:ss,nnnZ info hostd[***] [Originator@*** sub=Vimsvc.ha-eventmgr] Event ***: The ramdisk 'tmp' is full.  As a result, the file /tmp/bootbank.lck could not be written.

Environment

Vmware ESXi 7.*

Cause

This is due to the ramdisk 'tmp' is full.

Resolution

To increase the free space in the /tmp directory, referencing resources such as 'ESXi host not responding , /tmp folder shows high usage(90%-100%)'.

Additional Information

How to back up and restore the ESXi host configuration