Azure DevOps api command Get Work Item - Not able to use the $expand parameter : The value .. is not valid for Nullable

when I would like to expand the relations / any of the expand options in Azure DevOps 'Get WorkItem' api call, see documentation

https://learn.microsoft.com/en-us/rest/api/azure/devops/wit/work-items/get-work-item?view=azure-devops-rest-7.1&tabs=HTTP#workitemexpand

I can't get any usable results, instead I get a warning, that the value of the expand parameter is not valid.

When I send my call:

$workItem = Invoke-VSTeamRequest -Url "https://dev.azure.com/{org}/{project}/_apis/wit/workitems/{id}?api-version=7.1-preview.3&$expand=relations"

I get the error message:

"Message": "The value \u0027relations\u0027 is not valid for Nullable\u00601.\r\n"

When I use

$workItem = Invoke-VSTeamRequest -Url "https://dev.azure.com/{org}/{project}/_apis/wit/workitems/{id}?api-version=7.1-preview.3&expand=relations"

(without the preceding $), the parameter is ignored and I miss the required 'relations' array. Changing the api version has no effect.

Sorry, but I really have a knot in my brain actually. :(

Any help would be appreciated.

"Message": "The value \u0027relations\u0027 is not valid for Nullable\u00601.\r\n"

To solve this issue, we need to escape the $ character in the URL:

For example:

https://dev.azure.com/org/project/_apis/wit/workitems/workitemid?`$expand=relations&api-version=7.1-preview.3

You can use the following PowerShell sample:

$token = "PAT"

$url="https://dev.azure.com/{Org}/{Project}/_apis/wit/workitems/{ID}?`$expand=relations&api-version=7.1-preview.3"

$token = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$($token)"))

$response = Invoke-RestMethod -Uri $url -Headers @{Authorization = "Basic $token"} -Method Get  -ContentType application/json

Write-Host "$response"