Fail to update a server from 1.13.2 to 1.14.1

Hello

We are running a vanilla server on verygames.net, and we would like to update our map on 1.14.1. 

The problem is that every time we try to update the map, we're spawning in the nether's roof above the bedrock and on another seed, but on 1.14 ! The server's administrator told me that he can run the map on local and on 1.14 properly but after the uploading, we're on the situation I described earlier. We tried the traditional way to update a server. Do you have any piece of advice for us ? Thanks in advance.

Best regards.