I noticed this on the new EventLogging error dashboard. We are second-worst in schemas with errors.
It is passing a string for eventId where integer is expected:
u'341802' is not of type u'integer'
3226394 EventLogging {"event":{"version":"1.5","eventId":"341802","notificationType":"welcome","notificationGroup":"positive","sender":"-1","recipientUserId":3810264,"recipientEditCount":0,"deliveryMethod":"web"},"schema":"Echo","revision":7731316,"clientValidated":false,"wiki":"mediawikiwiki","recvFrom":"mw1007","timestamp":1445450213,"webHost":"127.0.0.1:9005","userAgent":"curl/7.35.0"}