As this is the first information to find with a search engine and people still looking for this compatibility, I could add some of my findings to save some time and hazzle for people interested.

### Some Explanation for Vanilla ###
The Space Elevator is working as a train station Up and train ...

Just to complement previous findings. Trying to host in on a different platform. In this case Factorio 1.1.5 dedicated server on Ubuntu will crash on load with the same error


Stack trace logging done
18.557 Warning Logger.cpp:526: Symbols.size() == 17, usedSize == 14
18.557 Error ...

0.000 2020-12-04 20:31:20; Factorio 1.1.5 (build 57246, win64, steam)
0.000 Operating system: Windows 10 (version 2004)
0.001 Program arguments: "F:\Games\Steam\steamapps\common\Factorio\bin\x64\Factorio.exe"
0.001 Read data path: F:/Games/Steam/steamapps/common/Factorio/data
0.001 Write data ...

We got the same issue here with our Multiplayer Game:

Having played without issues on 1.1.3-1 and now on 1.1.5 can´t load/host/convert the save file. Always getting issue:
38.796 Canceling manager upgrade of fast-underground-belt -> null because it is no longer a valid upgrade.
38.796 Canceling ...