Lost video file

[Sogolumbo]

It seems like my audapolis project lost the connection to a video file.
I changed from 0.2.1 to 0.2.2-pre4 and moved the project and the video file together (they remain next to each other).

actual behaviour
When I open the preview I see 'video missing' icon. When I export I get black video.

expected behaviour
Error message with some hint on how to fix the problem.