Prerequisites

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Steps to reproduce

Said cmdlets try to glean the desired encoding from the encoding attribute of an [xml] instance's XML declaration.

However, it is possible to have an XML declaration without such an attribute, which unexpectedly causes an error, because the code seemingly makes the assumption that this attribute is always there:

# Note: If you remove the XML declaration or add a valid "encoding" attribute, the problem goes away.
Invoke-RestMethod https://postman-echo.com/post -Method POST -ContentType text/xml -Body ([xml] '<?xml version="1.0"?><foo/>')

Expected behavior

The call should succeed and output a [pscustomobject] instance.

Actual behavior

The call fails with the following error:

Invoke-RestMethod: '' is not a supported encoding name. [...]

Error details

No response

Environment data

PowerShell Core 7.4.0-preview.1

Visuals

No response