A few months ago we started to publish our PowerShell modules to PowerShellGallery. PowerShellGallery visualizes the PSData defined in PrivateData of module manifest, which got introduced in PowerShell 5.

# Private data to pass to the module specified in RootModule/ModuleToProcess. This may also contain a PSData hashtable with additional module metadata used by PowerShell.
PrivateData = @{

    PSData = @{

        # Tags applied to this module. These help with module discovery in online galleries.
        # Tags = @()

        # A URL to the license for this module.
        # LicenseUri = ''

        # A URL to the main website for this project.
        # ProjectUri = ''

        # A URL to an icon representing this module.
        # IconUri = ''

        # ReleaseNotes of this module
        # ReleaseNotes = ''

    } # End of PSData hashtable

} # End of PrivateData hashtable

PrivateData part of a module manifest file created with the New-ModuleManifest Cmdlet of PowerShell 5.

Because of that we extended the module manifest files of our existing modules with the PrivateData hashtable as follows.

# Private data to pass to the module specified in RootModule/ModuleToProcess.
PrivateData = @{

    PSData = @{

        # Tags applied to this module. These help with module discovery in online galleries.
        Tags = @('dfch', 'PowerShell', 'Appclusive', 'Automation', 'OData')

        # A URL to the license for this module.
        LicenseUri = 'https://github.com/dfensgmbh/biz.dfch.PS.Appclusive.Client/blob/master/LICENSE'

        # A URL to the main website for this project.
        ProjectUri = 'https://github.com/dfensgmbh/biz.dfch.PS.Appclusive.Client'

        # A URL to an icon representing this module.
        IconUri = 'https://raw.githubusercontent.com/dfensgmbh/biz.dfch.PS.Appclusive.Client/master/logo-32x32.png'

        # ReleaseNotes of this module
        ReleaseNotes = 'Initial Release`
}

PSData hashtable got introduced with PowerShell 5. As most of our PowerShell modules have to be compatible with PowerShell 3 we verified, if the module manifest files created with PowerShell 5 are still compatible with PowerShell 3. They are. The only problem is, that the Tags, as defined in the example above, are causing problems in PowerShell 3 during the import of the module.

During the execution of the Import-Module Cmdlet the following error occurs.

iex : At line:257 char:18
+         Tags = @("dfch", "PowerShell", "Appclusive", "Automation", "OData")
+                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Executable script code found in signature block.
In C:\Program Files\WindowsPowerShell\Modules\biz.dfch.PS.Appclusive.Client\biz.dfch.PS.Appclusive.Client.psm1:35 Char:56
+     $Manifest = (Get-Content -raw $ManifestPathAndFile) | iex;
+                                                           ~~~
    + CategoryInfo          : ParserError: (:) [Invoke-Expression], ParseException
    + FullyQualifiedErrorId : TokenAfterEndOfValidScriptText,Microsoft.PowerShell.Commands.InvokeExpressionCommand

Import-Module : The module to process "biz.dfch.PS.Appclusive.Client.psm1", listed in field "ModuleToProcess/RootModule" of module 
manifest "C:\Program Files\WindowsPowerShell\Modules\biz.dfch.PS.Appclusive.Client\biz.dfch.PS.Appclusive.Client.psd1" was not processed
because no valid module was found in any module directory.
At line:1 char:1
+ Import-Module biz.dfch.PS.Appclusive.Client
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ResourceUnavailable: (biz.dfch.PS.Appclusive.Client:String) [Import-Module], PSInvalidOperationException
    + FullyQualifiedErrorId : Modules_ModuleFileNotFound,Microsoft.PowerShell.Commands.ImportModuleCommand

After an analysis of the problem I figured out, that the Tags have to be defined differently to be compatible with PowerShell 3.

The formats supported by PowerShell 5:

Tags = @("dfch", "PowerShell", "Appclusive", "Automation", "OData")
Tags = 'dfch', 'PowerShell', 'Appclusive', 'Automation', 'OData'

The format supported by PowerShell 3:

Tags = 'dfch', 'PowerShell', 'Appclusive', 'Automation', 'OData'

Changing the format of the Tags to the format compatible with PowerShell 3 solved my problem.

P.S.
Testing the module manifest with the Test-ModuleManifest Cmdlet of PowerShell 3 succeeds for both formats…

PS C:\windows\system32> Test-ModuleManifest -Path 'PATH\TO\MODULE_MANIFEST\example.psd1'