Name	Description
AgentNotReachable
AgentNotRunning
AgentUploadFailed
AgentUploadTimedout
InstallTimedout
NotEnoughSpaceOnDevice
PrepareToUpgradeFailed
SignatureVerificationFailed
UnknownInstallerError

         <simpleType xmlns="http://www.w3.org/2001/XMLSchema" xmlns:vsan="urn:vsan" name="AgentInstallFailedReason">
            <restriction base="xsd:string">
               <enumeration value="NotEnoughSpaceOnDevice"/>
               <enumeration value="PrepareToUpgradeFailed"/>
               <enumeration value="AgentNotRunning"/>
               <enumeration value="AgentNotReachable"/>
               <enumeration value="InstallTimedout"/>
               <enumeration value="SignatureVerificationFailed"/>
               <enumeration value="AgentUploadFailed"/>
               <enumeration value="AgentUploadTimedout"/>
               <enumeration value="UnknownInstallerError"/>
            </restriction>
         </simpleType>

Enum - AgentInstallFailedReason(vim.fault.AgentInstallFailed.Reason)

Enum Description