If receiving this error, this indicates that either nginx or httpd (or another reverse proxy) is being used which is limiting the size of the body request, and therefore returning this error code. This is different than having an issue uploading through the UI, and this article should not be followed for issues with only UI upload problems. In this case, there are settings on the reverse proxy that work around this issue (this could be set at a global level as well, so check all config files associated with your reverse proxy).