updated from v2.3.2 Windows to v2.4 and got the following error:
System.InvalidOperationException: Config Error ---> Newtonsoft.Json.JsonSerializationException: Error resolving type specified in JSON 'BizHawk.Emulation.Common.NullEmulator+NullEmulatorSettings, BizHawk.Emulation.Common'. Path 'CoreSettings['BizHawk.Emulation.Common.NullEmulator'].$type', line 1561, position 101. ---> Newtonsoft.Json.JsonSerializationException: Could not find type 'BizHawk.Emulation.Common.NullEmulator+NullEmulatorSettings' in assembly 'BizHawk.Emulation.Common, Version=2.4.0.1, Culture=neutral, PublicKeyToken=null'.
at Newtonsoft.Json.Serialization.DefaultSerializationBinder.GetTypeFromTypeNameKey(StructMultiKey`2 typeNameKey)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at Newtonsoft.Json.Serialization.DefaultSerializationBinder.BindToType(String assemblyName, String typeName)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ResolveTypeName(JsonReader reader, Type& objectType, JsonContract& contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, String qualifiedTypeName)
--- End of inner exception stack trace ---
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ResolveTypeName(JsonReader reader, Type& objectType, JsonContract& contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, String qualifiedTypeName)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadMetadataProperties(JsonReader reader, Type& objectType, JsonContract& contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue, Object& newValue, String& id)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateDictionary(IDictionary dictionary, JsonReader reader, JsonDictionaryContract contract, JsonProperty containerProperty, String id)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.SetPropertyValue(JsonProperty property, JsonConverter propertyConverter, JsonContainerContract containerContract, JsonProperty containerProperty, JsonReader reader, Object target)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(Object newObject, JsonReader reader, JsonObjectContract contract, JsonProperty member, String id)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
at BizHawk.Client.Common.ConfigService.Load[T](String filepath)
--- End of inner exception stack trace ---
at BizHawk.Client.Common.ConfigService.Load[T](String filepath)
at BizHawk.Client.EmuHawk.Program.SubMain(String[] args)
Then
Since your config file is corrupted or from a different BizHawk version, we're going to recreate it. Back it up before proceeding if you want to investigate further.
I dunno if that first error is the result of the 2nd error.