Why does iMovie stop exporting my movie 1/2 through?

It might help if you tell us more.

Right-click on one of the Event Clips and select Reveal in Finder.

Right click on one of the Finder Clips and select OPEN WITH/...QUICKTIME PLAYER.

In QuickTime Player, type the letter i while holding down the Command Key. That should open the inspector.

Tell us the dimensions of the clip and everything that is next to the word FORMAT:

Thanks.

Is this shot with a camcorder? If so make and model?

Or was it a screen capture?

OK That is an awesome camera. I am thinking of getting one myself. You may get better answers if you ask the question again and include GoPro in the question title. Then anyone who has one of these cameras will be sure to look at it.

Since I don't have the camera, I can only guess.

1) Go to FILE/PROJECT PROPERTIES. Is aspect ratio set to 4:3? (your movie is 1920x1440 in the inspector, so you should be using a 4:3 aspect ratio)

2) This is larger than the standard 1920x1080 movie. I would suggest totally turning off your Mac before trying to export. Then restart. This will free up your memory and swap files.

3) How much memory is installed on your Mac? Additional memory is available at sites like Macsales.com and crucial.com for reasonable prices.

4) If the 720P version finishes, it is likely a memory issue. You can test this further by shortening the movie. To do this, select the Project in the Project Library View (where you see all projects at once). With the project selected, click FILE/DUPLICATE PROJECT and give this new project a name like Short Version. Open this duplicate project and delete half the clips. Then try to export at 1080. If it finishes, you know it is a memory issue. If it still doesn't finish, try duplicating again and get it down to 3 minutes and try again.

5) Try googling GoPro and iMovie and see if there are any other sites where GoPro users share advice.

If I think of anything else I will add it later.