Same error here. On platform 188.8.131.52, Lifetime or SC.
When publishing via Studio (184.108.40.206) the problem doesn't occur.
Pretty sure I reported this as a bug ages ago.
Same error here on 220.127.116.11
This problem was already fixed in the versions 18.104.22.168 and 22.214.171.124 (Platform Server .NET and Java).
The bug caused two different types in OutSystems (for example, Integer List and User Identifier List) to be translated to the same underlying type (in this case List<int>), resulting in a compilation error as you've seen. The error would occur when compiling a Solution or Application. If you publish the eSpace alone, it should not happen.
You can avoid the problem by using a Record List instead of List for the OutSystems type.
I hope this information can help you overcome the problem.
Thanks Cláudia, that's informative, and good news :).
Great news... Thanks