There could be a couple of reasons why a replay file failed:
1. First make sure your replay file is one of the formats we currently accept:
- LoL we accept .bat, .rofl, .replay, .lrf and .cmd files only
- Dota2 we accept .dem files only
We will be adding new file types in the future.
2. Right now we only accept replay files for the current version/patch of the game. If your replay file is from an older version of the game it won’t work. Sorry.
3. If your replay is current and one of our accepted file formats, it's possible that the file is somehow corrupt. We notice that a small percentage of replay files just won't work. You can test this by trying to play the replay file in your game client. If it works and you can see the game play, try uploading it to us again.
If you have specific questions on this, feel free to open a ticket so we can troubleshoot it with you.