Hello, I was working with geoserver and I got an error. I searched for it on the internet and clicked on the first 3 links. Then I noticed that your site was opened and I saw that you also got the same error.

https://sedac.ciesin.columbia.edu/geoserver/wfs?request=Transaction

I don't know if this is unimportant to you, but I can easily see your layers on this site, for your information.

https://sedac.ciesin.columbia.edu/geoserver/web/wicket/bookmarkable/org.geoserver.web.demo.MapPreviewPage?5