Is the server patched with all the latest Windows Updates?  Never seen that error before but you can always check the logs too - C:\ProgramData\Veeam\Setup

In here there will be install logs and hopefully they can give more details.

I did some googling of this error and haven’t found anything, so please make sure to post back the resolution once you find it.  You can open a case with Support as well, but note that since you're using Community Edition, that’ll be best effort when they have the bandwidth.

Also, can you give us some information on what you’re installing on?  New machine?  Windows version?  Anything special?

The VM server is newly created and running on TrueNas Scale Virtualization.

VM Spec:

• CPU: 4 vCores
• RAM: 12 GB
• OS Storage: 128 GB

Windows Server Version: 

Full VBR Installation Log:

<03.10.2567 23:33:18]:INFO] Configuration file: E:\Setup\VBRSettings.xml
l03.10.2567 23:33:18]:INFO] Engine is starting...
.03.10.2567 23:33:18]:INFO] Creating wizard instance...
.03.10.2567 23:33:18]:INFO] Initializing engine components...
.03.10.2567 23:33:18]:INFO] Product configuration handler initialization...
.03.10.2567 23:33:18]:INFO] Parsing configuration file...
.03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup Catalog
g03.10.2567 23:33:18]:INFO] Catalog\VeeamBackupCatalog64.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam VSS Hardware Provider Service
e03.10.2567 23:33:18]:INFO] Packages\VeeamVssHwSnapshotProviderSvc.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup Update Service
e03.10.2567 23:33:18]:INFO] Backup\VeeamBackupUpdateService.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Backup\Server.x64.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup & Replication Console
e03.10.2567 23:33:18]:INFO] Backup\Shell.x64.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Installer Service
e03.10.2567 23:33:18]:INFO] Packages\VeeamInstallerSvc.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Distribution Service
e03.10.2567 23:33:18]:INFO] Packages\VeeamDistributionSvc.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup VSS Integration Service
e03.10.2567 23:33:18]:INFO] Packages\VeeamFilesysVssSvc.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Mount Service
e03.10.2567 23:33:18]:INFO] Packages\VeeamMountService.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup Transport
t03.10.2567 23:33:18]:INFO] Packages\VeeamTransport.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product VMware VDDK
K03.10.2567 23:33:18]:INFO] Packages\vmware-vddk.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Backup vPowerNFS
S03.10.2567 23:33:18]:INFO] Packages\vPowerNFS.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for Exchange
e03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForExchange.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for SharePoint
t03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForSharePoint.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for SQL
L03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForSQL.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for Active Directory
y03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForActiveDirectory.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for Oracle
e03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForOracle.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for Teams
s03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForTeams.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for PostgreSQL
L03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForPostgreSQL.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for SapHana
a03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForSapHana.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Explorer for MongoDB
B03.10.2567 23:33:18]:INFO] Explorers\VeeamExplorerForMongoDB.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Agent for Microsoft Windows Redistributable
e03.10.2567 23:33:18]:INFO] Packages\VAWRedist.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Agent for Linux Redistributable
e03.10.2567 23:33:18]:INFO] Packages\VALRedist.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Agent for Mac Redistributable
e03.10.2567 23:33:18]:INFO] Packages\VAMRedist.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Agent for Unix Redistributable
e03.10.2567 23:33:18]:INFO] Packages\VAURedist.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Veeam Plug-ins for Enterprise Applications Redistributable
e03.10.2567 23:33:18]:INFO] Packages\DbPluginRedist.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Kasten Plug-In for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Kasten\VeeamKastenPlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Kasten Plug-In UI extension Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Kasten\VeeamKastenPluginUI.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Nutanix AHV Plug-In for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Nutanix AHV\NutanixAHVPlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Nutanix AHV Plug-In Proxy for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Nutanix AHV\NutanixAHVPluginProxy.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Nutanix AHV Plug-In UI extension for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Nutanix AHV\NutanixAHVPluginUI.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product oVirt KVM Plug-in for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\KVM\KVMPlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product oVirt KVM Plug-In Proxy for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\KVM\KVMPluginProxy.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product oVirt KVM Plug-In UI extension for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\KVM\KVMPluginUI.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Proxmox Virtual Environment Plug-In for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Proxmox VE\PVEPlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Proxmox Virtual Environment Plug-In Proxy for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Proxmox VE\PVEPluginProxy.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Proxmox Virtual Environment Plug-In UI Extension for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Proxmox VE\PVEPluginUI.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product AWS Plug-In for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\AWS\AWSPlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product AWS Plug-In UI extension for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\AWS\AWSPluginUI.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Microsoft Azure Plug-In for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Microsoft Azure\MicrosoftAzurePlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Microsoft Azure Plug-In UI extension for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\Microsoft Azure\MicrosoftAzurePluginUI.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Google Cloud Platform Plug-In for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\GCP\GCPPlugin.msi
i03.10.2567 23:33:18]:INFO] ConfigurationParser: found new product Google Cloud Platform Plug-In UI extension for Veeam Backup & Replication
n03.10.2567 23:33:18]:INFO] Plugins\GCP\GCPPluginUI.msi
i03.10.2567 23:33:18]:INFO] Configuration file parse completed.
.03.10.2567 23:34:20]:INFO] Product configuration handler initialization completed
d03.10.2567 23:34:20]:INFO] Calculating disk space requirements...
.03.10.2567 23:34:20]:INFO] Installation path: 'C:\Program Files\Veeam'
'03.10.2567 23:34:20]:INFO] Required disk space:
:03.10.2567 23:34:20]:INFO] C:    20.47 GB
703.10.2567 23:34:20] ERROR] System.ArgumentOutOfRangeException: Index and length must refer to a location within the string. (Parameter 'length')
   at System.String.Substring(Int32 startIndex, Int32 length)
   at Veeam.Setup.Common.Util.GeneralUtilProvider.get_AssemblyPath()
   at Veeam.Setup.Wizard.PrereqEngineManager..ctor()
   at Veeam.Setup.Wizard.VmWizardEngine..ctor(String configFileFullPath, String configFileName, String strSerializeGuid, Window parent, Boolean& bRunWizard)
   at Veeam.Setup.Wizard.App.CreateWizard(String configFileName, String serializeGuid, Window parent)
   at Veeam.Setup.Common.Autorun.AutorunViewModel.RunWizard(Enum bundle)
   at Veeam.Setup.Autorun.WPF.Pages.AutorunPageViewModel.FinishAutorun(Bundle selectedBundle)
   at Veeam.Setup.Autorun.WPF.Pages.AutorunPageViewModel.<>c__DisplayClass20_0.<InitBundle>b__0(Object commandData)
   at Veeam.Setup.Wizard.WPF.DelegateCommand.Execute(Object parameter)
   at MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated)
   at System.Windows.Controls.Primitives.ButtonBase.OnClick()
   at System.Windows.Controls.Button.OnClick()
   at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
   at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
   at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Window.ShowHelper(Object booleanBox)
   at System.Windows.Window.Show()
   at System.Windows.Window.ShowDialog()
   at Veeam.Setup.Wizard.VmAutorunEngine.RunAutorun()
   at Veeam.Setup.Wizard.App.RunWizard()

Did you mount the ISO on the server or did you unpack the ISO?

It might be best to download the ISO again, your stored ISO might be damaged.

Are you using an x86-64 processor or ARM processor in your hypervisor?

I have tired both mount and unpack ISO and redownload the ISO.

I use x86-64 processor.

@unknown_q  I would suggest to try copying the VBR setup files to the local disk and running the installer if you are trying to install directly from the ISO. Also, ensure you run the installation with elevated administrator permissions

Copy the ISO locally to the server, then mount it virtually via the OS. Do not unpack

You wrote that this is a new VM with new Windows Installation.

Maybe reinstall the VM and test the setup again.

The specs you have for CPU/RAM seem low if this is to be an all-in-one setup.  You might want to bump it to 8 vCPU and 16GB of RAM as that is typically the minimum I go with.  You need to take in to account the VBR install, Postgres/SQL, and OS requirements for CPU/RAM.

Yeah, I agree….spec’s might be a little bit low.  I mean, I think it should work, but I usually end up increasing specs to around where Chris mentioned.  And since this is a new VM, I’d consider rolling out another new one to see if you get the same results.  I can’t speak at all about it running on TrueNAS as I’ve never tried.