Hi - I'm actually facing the same problem and I don't understand what causes it. I've noticed that it occurs when I try to use large file as a cover (succeeded with 1820KB file but failed with 2504KB file). Payload size does not seem to matter (it failed even with 1KB txt file). Is that the reason? Or am I doing anything wrong? I'm also using x64 portable on Windows. Commad: steghide.exe embed -ef empty.txt -cf image.jpg