Can't get past error 39

[HaloFinancial]

So I have about a 15 minute long video that I am trying to export but for some reason it is failing to export every single time and it is always near the end of the video and I can't work out why. I get 39 and I am writing with exporter H.264. The file type is H264 and the average timecode when it fails to finish the encode is 00:15:17:13. The video is mp.4 and the audio is AAC. Please help!