It is not possible to create a SignalR Service by using the Azure Portal.

No matter which Resource Name i choose, i get an error:

{
  "type": "MsPortalFx.Errors.AjaxError",
  "baseTypes": ["MsPortalFx.Errors.AjaxError", "MsPortalFx.Errors.Error"],
  "data": {
    "uri": "https://management.azure.com/api/invoke",
    "type": "POST",
    "pathAndQuery": "/subscriptions/xxxxxxxxxxx/providers/Microsoft.SignalRService/locations/westeurope/checkNameAvailability?api-version=2023-08-01-preview",
    "requestId": "xxxxxxxxxxxxxxxxxxxxxx",
    "failureCause": "",
    "sessionId": "xxxxxxxxxxxxxxxxxxxxx",
    "commandName": "Microsoft_Azure_SignalR.",
    "status": 500,
    "statusText": "error",
    "duration": 1357.2999999970198
  },
  "extension": "Microsoft_Azure_SignalR",
  "errorLevel": 2,
  "timestamp": 108418.60000000149,
  "name": "AjaxError",
  "innerErrors": [],
  "textStatus": "error",
  "errorThrown": "",
  "jqXHR": {
    "readyState": 4,
    "responseText": "{"error":{"code":"InternalServerError","message":"Unhandled Exception in Azure SignalR service. Please try again later."}}",
    "responseJSON": {
      "error": {
        "code": "InternalServerError",
        "message": "Unhandled Exception in Azure SignalR service. Please try again later."
      }
    },
    "status": 500,
    "statusText": "error"
  }
}