It's probably not a stored procedure because the error message is showing you the path to the file that's being saved. You should make sure that the uploader has privileges to store a file in Portals\0\HGBC_Images. Check the permissions.
Were you trying to upload the file using the DotNetNuke File Manager?
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Oops, yes you are using the File Manager! If you haven't done so already, look at
DotNetNuke File Manager.