Suffered this issue today with dgraph Cloud.
As @amaster507 I’ve deleted all the elements that were blocking this change and I’m still having the same isue
"resolving updateGQLSchema failed because rpc error: code = Unknown desc = succeeded in saving GraphQL schema but failed to alter Dgraph schema - GraphQL layer may exhibit unexpected behaviour, reapplying the old GraphQL schema may prevent any issues: Schema change not allowed from scalar to uid or vice versa while there is data for pred ...."
In ratel, it is possible to drop the infos attached to the predicate that’s giving the error. That fixes the issue.
On the other hand… I think that once we delete all the data by mutations, the schema should be able to change without doing this manual operation or requiring DQL