My point was that the sequence does not need to be rendered to export and I took from your posts that you were creating a fresh project in order to avoid rendering the sequence.
There are many people who keep background rendering off and do not force a render before they export. That (IMO) is a perfectly reasonable workflow. I have found it to be more reliable and efficient; if one is getting real time playback, why not? Clearly a rendered sequence will export faster than an unrendered one. But if the time to render and time to export are combined and compared to exporting an unrendered sequence, the latter wins on my machine. YMMV.
But for what you wanted to do, it seemed like a good alternative to me.
This is an old thread with a variety of systems, issues and error messages.
It would be easier to help if you could start a new thread, wherein you give your system specs –including your version of FCPX, the kind of media in your projects, your problem and what you've tried so far to solve your problem.