[PROBLEM] MoOde freezes, config pages won't load

[PJVervoorn]

More testing, I should have tried this before…
When I select one of the predefined yml files all is OK, I tried several V2 ymls; the problem occurs when using an uploaded file, that was downloaded from 8.3.9.
Did the format change from 8.3.9 to 9.0.x?
(The file validates OK when uploading.)