manhta You tested a 188MB file (which is bigger than the chunk size of 150MB, but smaller than the CloudFlare limit of 200MB ), but the problem is that files larger than the CloudFlare limit fail. And @Ninja said I have to increase the CloudFlare limit. But what would be the purpose of splitting the upload into smaller pieces if the CloudFlare limit must be increased to cover the total combined size anyway? I believe large files (>200MB in this case) uploaded through the activity stream postbox should be split into chunks and should succeed, even with the CloudFlare limit at 200MB, as it works from the profile/My Videos upload window! Please clarify.