Powershell: A positional parameter cannot be found that accepts argument "xxx"

Cmdlets in powershell accept a bunch of arguments. When these arguments are defined you can define a position for each of them.

This allows you to call a cmdlet without specifying the parameter name. So for the following cmdlet the path attribute is define with a position of 0 allowing you to skip typing -Path when invoking it and as such both the following will work.

Get-Item -Path C:\temp\thing.txtGet-Item C:\temp\thing.txt

However if you specify more arguments than there are positional parameters defined then you will get the error.

Get-Item C:\temp\thing.txt "*"

As this cmdlet does not know how to accept the second positional parameter you get the error. You can fix this by telling it what the parameter is meant to be.

Get-Item C:\temp\thing.txt -Filter "*"

I assume you are getting the error on the following line of code as it seems to be the only place you are not specifying the parameter names correctly, and maybe it is treating the = as a parameter and $username as another parameter.

Set-ADUser $user -userPrincipalName = $newname

Try specifying the parameter name for $user and removing the =

I had this issue after converting my Write-Host cmdlets to Write-Information and I was missing quotes and parens around the parameters. The cmdlet signatures are evidently not the same.

Write-Host this is a good idea $here
Write-Information this is a good idea $here <=BAD

This is the cmdlet signature that corrected after spending 20-30 minutes digging down the function stack...

Write-Information ("this is a good idea $here") <=GOOD

In my case it was the distinction between –(En dash) and -(Hyphen) as in:

Add-Type –Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"

and:

Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"

Dashes, Hyphens, and Minus signs oh my!