Create Incident with Powershell

[JamesLindsay]

I am looking for some advice on how to solve an issue I am having opening an incident using the REST API at /api/now/v1/table/incident. I have a PowerShell script that I am using to integrate with a monitoring source that will execute the script as an action to open an incident. What I am finding is that when I pass the JSON payload using:
$response = Invoke-RestMethod -Uri $ApiUrl -Method Post -Headers $headers -Body $CaseDetailsJson
The ticket that is created does not have several of the passed field values populated. Specifically, the "impact" field is passed the wrong value and the "assignment_group" and "description" fields are left empty. The very same payload pasted into a PostMan session works perfectly fine.

I build out the JSON with this:

$CaseDetails = @{
"impact" = $impact
"urgency" = $urgency
"cmdb_ci" = $cmdb_ci
"business_service" = $business_service
"u_categorization" = $u_categorization
"short_description" = $short_description
"description" = $description
"contact_type" = $contact_type
"assignment_group" = $assignment_group
}

$CaseDetailsJson = $CaseDetails | ConvertTo-Json -Compress

The headers used are:
$headers = @{
"Authorization" = "Basic $Credentials"
"Accept" = "application/json"
"Content-Type" = "application/json"
}

At this point I'm still keeping it very simple and testing with some very basic values knowing that from my monitoring event source, the description field could get complicated. As I said, I can take the exact same JSON produced from this script that I wrote to a text file for checking, paste it into Postman and I get exactly what I expect in the ticket. I am at a complete loss at why it snot working from PowerShell. Thank you for any insight or help you may provide.

[Rakesh18081]

It sounds like PowerShell isn't correctly formatting or transmitting the JSON payload as expected. Since the same payload works in Postman, here are a few things to check:
1. Ensure Proper JSON Formatting
PowerShell's ConvertTo-Json can sometimes alter the structure of the payload. Try using -Depth 10 to ensure nested objects are correctly formatted:
$CaseDetailsJson = $CaseDetails | ConvertTo-Json -Depth 10 -Compress

2. Verify Encoding
PowerShell may encode special characters differently than Postman. Try explicitly setting UTF-8 encoding:
$utf8Bytes = [System.Text.Encoding]::UTF8.GetBytes($CaseDetailsJson)
$response = Invoke-RestMethod -Uri $ApiUrl -Method Post -Headers $headers -Body $utf8Bytes -ContentType "application/json"

Log the headers of both postman and PowerShell and compare to see if postman is passing additional headers which are not present in PowerShell .

[JamesLindsay · Accepted solution]

At this point what I have found is that I was attempting the open the incident with a User in ServiceNow that did not have the ITIL role but, the user I was using in Postman did. Not sure why it took so long for me to see that delta. After adding the role it now works as designed. However, I am hoping to avoid the cost of another ITIL user license so I've started looking at what it might take to insert the record into an Import Set table instead.