Windows powershell not working11/23/2023 ![]() If we try to open a file, we get a helpful error message explaining why the system can’t allow it. When we don’t have permissions to do something, we expect that the system will alert us. ![]() Understanding the Effects of the Hyper-V Security Model That window overlaps another window that contains the output from Get-VM in an elevated session. To clarify that messy output, I ran gwmi -Namespace rootvirtualizationv2 -Class Msvm_ComputerSystem -Filter ‘Caption=”Virtual Machine”‘ as a non-privileged user and the system gave no output. The WMI provider behaves as it always has: However, only the PowerShell module has been changed. The PowerShell cmdlets that I tried now show an appropriate error message. The PowerShell behavior has changed in 2016: The session on the right was started by using Run as administrator. The session on the left was started normally. What happened? A surprise Live Migration? That means that the host has no virtual machines, right? So, if I run Get-VM and get nothing (2012/R2): So, you learn to interpret “I got nothing” to mean “no objects of that type exist”. What happens when you run a “Get” against objects that don’t exist? For example, what happens when I run Get-Job when no jobs are present? ![]() Seeing Effects of the Hyper-V Security Model in Action No insider secrets or pilfered knowledge were used in the creation of this material. ![]() So, everything that you’re going to see in this article originates from experienced (and repeatable) behavior. They obviously don’t have any externally-facing documentation, but they don’t have anything internal, either. So, I asked if they would give me the documentation on that - basically, anything on what caused that behavior. In other words, I was experiencing a side effect of designed behavior. The answer that came back pointed to the internal security coding of the module. I opened a case with Microsoft, and it wound up going all the way to the developers. I ran into some issues with WMI commands not working the way that I expected. Sometimes, it chooses to have no reaction at all.īefore I go too far, I want to make it clear that no documentation exists for the security model in Hyper-V’s WMI provider. The developers behind the Hyper-V WMI provider decide how it will react to any given WMI/CIM command that it receives. I told you all that about WMI so that this part would be easier to follow. Why Hyper-V PowerShell Cmdlets May Not Workīeyond minor things like incorrect syntax and environmental things like failed hardware, two common reasons prevent these tools from functioning as expected. The provider’s developer determines how it all functions behind the scenes. The object definitions and syntax of a provider all descend from the common standard, but they do nothing more than establish the way an interface should look. Get-CimInstance provides something of an analog to Get-WmiObject, but they are not interchangeable.įor any of this to ever make any sense, you need to understand one thing: anyone can write a CIM/WMI provider. Depending on where you look in Microsoft’s vast documentation, you might see pushes away from the Microsoft-specific WMI implementation toward the more standard CIM corollaries. As PowerShell gained popularity, WMI also gained popularity due to the relative ease of Get-WmiObject. Many WMI instructions involved VBS or WMIC. Traditionally, Microsoft has implemented CIM via Windows Management Instrumentation (WMI). By leveraging CIM, software and hardware manufacturers can provide APIs and controls with predictable, standardized behavior. These modules allow users, applications, and services to retrieve information and/or send commands to the managed system. Anyone can write CIM-conforming modules to work with their systems. CIM defines a number of interfaces pertaining to management. The Distributed Management Task Force (DMTF) maintains the CIM standard. CIM stands for “Common Information Model”. The WMI FoundationĪll tools, graphical or command-line, eventually work their way back to the only external interface that Hyper-V provides: its WIM/CIM provider. Most GUI tools are developed to avoid the problems that plague the command line, but the solutions aren’t always perfect. Sometimes these problems arise with the module that Microsoft provides other times, they manifest with third-party tools. I occasionally receive questions about Hyper-V-related PowerShell cmdlets not working as expected.
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