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Why am getting "Invalid" data errors when trying to make Login and/or GetUserAlerts API calls?
When trying to make calls to Client Alerts API's, you will often get "Invalid" data error, or you will get a successful response with no data in the response.
The reason you may be getting the "Invalid" data error, is you MUST URL-encode the ClientAlertsAuthToken for the Login call and both the SessionData and SessionID when making a GetUserAlerts call (when making the call via URL).
For more details on the steps to take in order to make a GetUserAlerts call, refer to article https://ebaydts.com/eBayKBDetails?KBid=1973
Client Alerts Call Reference: http://developer.ebay.com/DevZone/client-alerts/docs/CallRef/index.html