Error exporting, recieving error 39 or when successful doesnt export the whole video properly

I keep on recieving an error for my video, its supposed to come out around 50 minutes but sometimes when I export it I recieve an Error and the other times I export it it will play for 8 minutes or so then skip to the end even the the mp4 file reads 50 minutes. Here is the info for the error:
Error compiling movie.

Export error

Error finishing encode.

writing with exporter: h.264
writing to file: C:Users\goblin\OneDrive\Desktop\videosyt\dishonored1_3.mp4

around time code 49:27:37
component: H.264 of type exporter

selector: 9

Error Code: 39
Really hoping not to lose this footage, its the 3rd video of a series.