There was an error passing information between the third party you just came from and eBay. Error code: 20.1.5::
What is the problem?
This error message can occur if the SessID obtained from the GetSessionID request has expired. SessIDs obtained from GetSessionID have a limited life, and your request to signin.ebay.com must be made within that time span (of the order of a few minutes).
To verify the problem lies with the SessID parameter, you can remove the SessID parameter from the request. If the following leads you to the eBay signin page, the problem likely is with the SessID parameter :