how do i fix a missing trailer

General Discussions
1

Can a trailer be manually added to a movie kind of like adding a new poster?

2

If you have a video file of the trailer, then yes.

It is called ‘Local Extras’
For this to work, you need to put the movie in question into its own subfolder and add the trailer video with a specially-crafted file name.

Movies /
   Movie Title (2017) /
      Movie Title (2017).mp4
      Teaser-trailer.mp4

see https://support.plex.tv/hc/en-us/articles/200220677-Local-Media-Assets-Movies