[Haskell-cafe] documentation build failing in hackage?

Sorry if this has been asked/discussed previously It seems that there are many packages in which the documentation is not generated. That is the visible effect since there is no indication if the build process failed or not. Could anyone give me some hints? I did a lazy look at the hackage2 documentation but I found nothing about that. Only that it is possible to upload the documentation if the build bot fails... -- Alberto.