Failed to save protobuf data to oxide.users.data (InvalidOperationException: out of sync)

Code:

Failed to save protobuf data to oxide.users.data (InvalidOperationException: out of sync)
at System.Collections.Generic.Dictionary`2+Enumerator[System.String,Oxide.Core.Libraries.UserData].VerifyState () [0x00000] in <filename unknown>:0
at System.Collections.Generic.Dictionary`2+Enumerator[System.String,Oxide.Core.Libraries.UserData].MoveNext () [0x00000] in <filename unknown>:0
at ProtoBuf.Meta.TypeModel.TrySerializeAuxiliaryType (ProtoBuf.ProtoWriter writer, System.Type type, DataFormat format, Int32 tag, System.Object value, Boolean isInsideList) [0x00000] in <filename unknown>:0
at ProtoBuf.Meta.TypeModel.SerializeCore (ProtoBuf.ProtoWriter writer, System.Object value) [0x00000] in <filename unknown>:0
at ProtoBuf.Meta.TypeModel.Serialize (System.IO.Stream dest, System.Object value, ProtoBuf.SerializationContext context) [0x00000] in <filename unknown>:0
at ProtoBuf.Meta.TypeModel.Serialize (System.IO.Stream dest, System.Object value) [0x00000] in <filename unknown>:0
at ProtoBuf.Serializer.Serialize[Dictionary`2] (System.IO.Stream destination, System.Collections.Generic.Dictionary`2 instance) [0x00000] in <filename unknown>:0
at Oxide.Core.ProtoStorage.Save[Dictionary`2] (System.Collections.Generic.Dictionary`2 data, System.String[] subPaths) [0x00000] in <filename unknown>:0