Powershell won't install almost any module using install-module

Question

My Powershell v5.1 won't install almost any module automatically using install-module whereas manually installation does work.

First, when I run install-module, it would download the module then throw an error, say the pscx module:

PackageManagement\Install-Package : Package 'Pscx' failed to be installed because: Specified cast is not valid.
At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\2.0.4\PSModule.psm1:9307 char:21
+ ...          $null = PackageManagement\Install-Package @PSBoundParameters
+                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidResult: (Pscx:String) [Install-Package], Exception
    + FullyQualifiedErrorId : Package '{0}' failed to be installed because: {1},Microsoft.PowerShell.PackageManag
   ement.Cmdlets.InstallPackage

What I can do now is to manually download the module and use import-module myself. The error occurs almost every time when I'm trying to install any module through this cmdlet. How can I address this problem?

For troubleshooting, Get-PSRepository gives me this:

PS C:\> Get-PSRepository

Name                      InstallationPolicy   SourceLocation
----                      ------------------   --------------
PSGallery                 Trusted              https://www.powershellgallery.com/api/v2
GalleryRolling            Trusted              https://www.poshtestgallery.com/api/v2/

---

EDIT:

Got the same error when trying to use Save-Module:

PS C:\> Find-Module -Name 'pscx' | Save-Module -Path "G:\Temp\System Documents\WindowsPowerShell\Modules"
WARNING: Package 'Pscx' failed to be installed because: Specified cast is not valid.
WARNING: Package 'Pscx' failed to install.
PackageManagement\Save-Package : Unable to save the module 'Pscx'.
At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\2.0.4\PSModule.psm1:11331 char:25
+ ...             $null = PackageManagement\Save-Package @PSBoundParameters
+                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (Microsoft.Power...ets.SavePackage:SavePackage) [Save-Packag
   e], Exception
    + FullyQualifiedErrorId : ProviderFailToDownloadFile,Microsoft.PowerShell.PackageManagement.Cmdlets.Save
   Package

It downloaded the package then displays the WARNING.

When using the Find-Module alone, the result is:

PS C:\> Find-Module -Name 'pscx'

Version              Name                                Repository           Description
-------              ----                                ----------           -----------
3.3.2                Pscx                                PSGallery            PowerShell Community Extensi...

---

EDIT 2:

Oh I forgot to say that there are no files created in the specific download folder after the download process bar disappeared. Does that mean the download has failed?

---

EDIT 3: @Sage Pourpre

1. Debugging log
2. I Always run PS as administrator.
3. -Scope CurrentUser throws the same error.

4. Both PS C:\> Uninstall-Module -Name "PowerShellGet" and PS C:\> Uninstall-Script -Name "PowerShellGet" -RequiredVersion 2.0.3 produce the same result.

   PackageManagement\Uninstall-Package : No match was found for the specified search criteria and script names 'PowerShellGet'. At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\2.0.4\PSModule.psm1:12343 char:21

   • ... $null = PackageManagement\Uninstall-Package @PSBoundParameters

   • + CategoryInfo          : ObjectNotFound: (Microsoft.Power...ninstallPackage:UninstallPackage) [Uninstal
     l-Package], Exception
     + FullyQualifiedErrorId : NoMatchFound,Microsoft.PowerShell.PackageManagement.Cmdlets.UninstallPackage
     

Then I tried to list available modules:

PS C:\> Get-Module -ListAvailable


    Directory: G:\Temp\System Documents\WindowsPowerShell\Modules


ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Binary     2.7.1.7    ISESteroids                         {Get-PSSharperData, Add-SteroidsContextMenuComma...
Script     1.2        Use-RawPipeline                     {Invoke-NativeCommand, Receive-RawPipeline, Get-...


    Directory: C:\Program Files\WindowsPowerShell\Modules


ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     1.0.1      Microsoft.PowerShell.Operation.V... {Get-OperationValidation, Invoke-OperationValida...
Script     1.2.4      PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider,...
Script     4.5.0      Pester                              {Describe, Context, It, Should...}
Script     2.0.4      PowerShellGet                       {Find-Command, Find-DSCResource, Find-Module, Fi...
Script     2.0.3      PowerShellGet                       {Find-Command, Find-DSCResource, Find-Module, Fi...
Script     1.2        PSReadline                          {Get-PSReadlineKeyHandler, Set-PSReadlineKeyHand...


    Directory: C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules


ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Manifest   1.0.0.0    AppBackgroundTask                   {Disable-AppBackgroundTaskDiagnosticLog, Enable-...
Manifest   2.0.0.0    AppLocker                           {Get-AppLockerFileInformation, Get-AppLockerPoli...
Manifest   1.0.0.0    AppvClient                          {Add-AppvClientConnectionGroup, Add-AppvClientPa...
Manifest   2.0.0.0    Appx                                {Add-AppxPackage, Get-AppxPackage, Get-AppxPacka...
Script     1.0.0.0    AssignedAccess                      {Clear-AssignedAccess, Get-AssignedAccess, Set-A...
Manifest   1.0.0.0    BitLocker                           {Unlock-BitLocker, Suspend-BitLocker, Resume-Bit...
etc...

And Get-InstalledModule

PS C:\> Get-InstalledModule -Name "PowerShellGet" -RequiredVersion 2.0.3
PackageManagement\Get-Package : No match was found for the specified search criteria and module names
'PowerShellGet'.
At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\2.0.4\PSModule.psm1:9050 char:9
+         PackageManagement\Get-Package @PSBoundParameters | Microsoft. ...
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (Microsoft.Power...lets.GetPackage:GetPackage) [Get-Package],
   Exception
    + FullyQualifiedErrorId : NoMatchFound,Microsoft.PowerShell.PackageManagement.Cmdlets.GetPackage

Answer 1

Finally solved by:

[Net.ServicePointManager]::SecurityProtocol = "tls12"

The solution is from the following blog posted by vanBrenk:

Trying to install a PowerShell module behind a proxy? Chances are you're getting this error: "Unable to resolve package source 'https://www.powershellgallery.com/api/v2/'". Turns out it isn't allowed through your proxy server [...] Now every command you run is sent and allowed through the proxy.