Why does media sometimes fail to attach to my posts?
If your post is successful, but your attachment is missing, it’s most likely because the server instance you are on was too busy at that moment. This issue is mostly common on instances with a lot of activity (ie. Mastodon.Social). This issue also occurs on the instance website on occasion.
If your post won't publish because of an error with your media, it’s most likely because the server doesn’t like the size or format of your media. We are working to improve proper conversion or compression of common media types in our app so media gets accepted by the server with more success.