Problem when trying to export a MOV from Animate. Error message showing up. Need help

Working in Animate CC. drawing over a png sequence and ultimately deleting the photo sequence before exporting the drawings on a alpha channel and import it back over my video in premiere Pro. I made a few exports that worked so i started the whole thing. Now i try to export again and i have this screen popin up. 
 It,s in french but it says "Could not read from the source. Please check if it has moved or been deleted."

can someone help me out here ? why did it works at starts and now it doesnt work and i have to do these exports soon enough..!

I've seen that some people had the same problem than me but i didnt found the good way to make it work so sorry if it seems irellevant but i'm stuck right now. 

Thanks for the feedback