19:02 [Info] Loading Oxide Core v2.0.4054...
19:02 [Error] Failed to load protobuf data from oxide.users.data (ProtoException: Invalid field in source data: 0)
at ProtoBuf.ProtoReader.ReadFieldHeader () [0x00058] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.TryDeserializeAuxiliaryType (ProtoBuf.ProtoReader reader, ProtoBuf.DataFormat format, System.Int32 tag, System.Type type, System.Object& value, System.Boolean skipOtherFields, System.Boolean asListItem, System.Boolean autoCreate, System.Boolean insideList) [0x000a8] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.TryDeserializeList (ProtoBuf.Meta.TypeModel model, ProtoBuf.ProtoReader reader, ProtoBuf.DataFormat format, System.Int32 tag, System.Type listType, System.Type itemType, System.Object& value) [0x000aa] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.TryDeserializeAuxiliaryType (ProtoBuf.ProtoReader reader, ProtoBuf.DataFormat format, System.Int32 tag, System.Type type, System.Object& value, System.Boolean skipOtherFields, System.Boolean asListItem, System.Boolean autoCreate, System.Boolean insideList) [0x0006f] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.DeserializeCore (ProtoBuf.ProtoReader reader, System.Type type, System.Object value, System.Boolean noAutoCreate) [0x0001f] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.Deserialize (System.IO.Stream source, System.Object value, System.Type type, ProtoBuf.SerializationContext context) [0x00021] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.Deserialize (System.IO.Stream source, System.Object value, System.Type type) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Serializer.Deserialize[T] (System.IO.Stream source) [0x00005] in <271c58b7a8684db5a2c92be17a81f252>:0
at Oxide.Core.ProtoStorage.Load[T] (System.String[] subPaths) [0x0001d] in <157a94ee66ab4a7991faecd1eb84be3b>:0
19:02 [Error] Failed to load protobuf data from oxide.groups.data (ProtoException: Invalid field in source data: 0)
at ProtoBuf.ProtoReader.ReadFieldHeader () [0x00058] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.TryDeserializeAuxiliaryType (ProtoBuf.ProtoReader reader, ProtoBuf.DataFormat format, System.Int32 tag, System.Type type, System.Object& value, System.Boolean skipOtherFields, System.Boolean asListItem, System.Boolean autoCreate, System.Boolean insideList) [0x000a8] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.TryDeserializeList (ProtoBuf.Meta.TypeModel model, ProtoBuf.ProtoReader reader, ProtoBuf.DataFormat format, System.Int32 tag, System.Type listType, System.Type itemType, System.Object& value) [0x000aa] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.TryDeserializeAuxiliaryType (ProtoBuf.ProtoReader reader, ProtoBuf.DataFormat format, System.Int32 tag, System.Type type, System.Object& value, System.Boolean skipOtherFields, System.Boolean asListItem, System.Boolean autoCreate, System.Boolean insideList) [0x0006f] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.DeserializeCore (ProtoBuf.ProtoReader reader, System.Type type, System.Object value, System.Boolean noAutoCreate) [0x0001f] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.Deserialize (System.IO.Stream source, System.Object value, System.Type type, ProtoBuf.SerializationContext context) [0x00021] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Meta.TypeModel.Deserialize (System.IO.Stream source, System.Object value, System.Type type) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0
at ProtoBuf.Serializer.Deserialize[T] (System.IO.Stream source) [0x00005] in <271c58b7a8684db5a2c92be17a81f252>:0
at Oxide.Core.ProtoStorage.Load[T] (System.String[] subPaths) [0x0001d] in <157a94ee66ab4a7991faecd1eb84be3b>:0

Looks like your data files got corrupted somehow, this can sometimes happen when a server crashes during save. Try removing the oxide files from the oxide/data directory and see if that fixes it.

Yeah. It also seems there was an automatic saved right when that happened which made that backup file useless also. :D
I had to roll back to the day before.
Well, I did not delete the data but wipe the server before doing that.
By now the server is stable.