Any chance for a fix please?

Failed to call hook 'OnServerSave' on plugin 'DisbandedTeamRestore v1.5.1' (InvalidCastException: Specified cast is not valid.)
  at Steamworks.InventoryDef.Equals (System.Object p) [0x00000] in <95c973cf853840e48d5534d70d14598e>:0 
  at System.Collections.Generic.ObjectEqualityComparer`1[T].IndexOf (T[] array, T value, System.Int32 startIndex, System.Int32 count) [0x0003d] in <ff4e3fe86250407285eaebda8f185c35>:0 
  at System.Array.IndexOfImpl[T] (T[] array, T value, System.Int32 startIndex, System.Int32 count) [0x00005] in <ff4e3fe86250407285eaebda8f185c35>:0 
  at System.Array.IndexOf[T] (T[] array, T value, System.Int32 startIndex, System.Int32 count) [0x00044] in <ff4e3fe86250407285eaebda8f185c35>:0 
  at System.Collections.Generic.List`1[T].IndexOf (T item) [0x00000] in <ff4e3fe86250407285eaebda8f185c35>:0 
  at System.Collections.Generic.List`1[T].Contains (T item) [0x00008] in <ff4e3fe86250407285eaebda8f185c35>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonProperty property, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x00062] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContainerContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonProperty property, Newtonsoft.Json.Serialization.JsonContract& memberContract, System.Object& memberValue) [0x000c7] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList (Newtonsoft.Json.JsonWriter writer, System.Collections.IEnumerable values, Newtonsoft.Json.Serialization.JsonArrayContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000d6] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000d4] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList (Newtonsoft.Json.JsonWriter writer, System.Collections.IEnumerable values, Newtonsoft.Json.Serialization.JsonArrayContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000d6] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000d4] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList (Newtonsoft.Json.JsonWriter writer, System.Collections.IEnumerable values, Newtonsoft.Json.Serialization.JsonArrayContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000d6] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000d4] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeDictionary (Newtonsoft.Json.JsonWriter writer, System.Collections.IDictionary values, Newtonsoft.Json.Serialization.JsonDictionaryContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0017b] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0013a] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract collectionContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue (Newtonsoft.Json.JsonWriter writer, System.Object value, Newtonsoft.Json.Serialization.JsonContract valueContract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty) [0x000b0] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize (Newtonsoft.Json.JsonWriter jsonWriter, System.Object value, System.Type objectType) [0x00079] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.JsonSerializer.SerializeInternal (Newtonsoft.Json.JsonWriter jsonWriter, System.Object value, System.Type objectType) [0x00253] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.JsonSerializer.Serialize (Newtonsoft.Json.JsonWriter jsonWriter, System.Object value, System.Type objectType) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.JsonConvert.SerializeObjectInternal (System.Object value, System.Type type, Newtonsoft.Json.JsonSerializer jsonSerializer) [0x00028] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.JsonConvert.SerializeObject (System.Object value, System.Type type, Newtonsoft.Json.Formatting formatting, Newtonsoft.Json.JsonSerializerSettings settings) [0x0000e] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Newtonsoft.Json.JsonConvert.SerializeObject (System.Object value, Newtonsoft.Json.Formatting formatting, Newtonsoft.Json.JsonSerializerSettings settings) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0 
  at Oxide.Core.Configuration.DynamicConfigFile.WriteObject[T] (T config, System.Boolean sync, System.String filename) [0x00039] in <beb2b64691c64e2b95b99491bd85442c>:0 
  at Oxide.Core.DataFileSystem.WriteObject[T] (System.String name, T Object, System.Boolean sync) [0x00007] in <beb2b64691c64e2b95b99491bd85442c>:0 
  at Oxide.Plugins.DisbandedTeamRestore.SaveDataFile[T] (System.String fileName, T data) [0x00039] in <8fed3c6a14cb42a7bcb448c18fc798fe>:0 
  at Oxide.Plugins.DisbandedTeamRestore.SaveTeams (System.Boolean shutdownWasSuccessful) [0x00078] in <8fed3c6a14cb42a7bcb448c18fc798fe>:0 
  at Oxide.Plugins.DisbandedTeamRestore.OnServerSave () [0x00018] in <8fed3c6a14cb42a7bcb448c18fc798fe>:0 
  at Oxide.Plugins.DisbandedTeamRestore.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00555] in <8fed3c6a14cb42a7bcb448c18fc798fe>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <795304323ac74a298b8ed190a1dfa739>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <beb2b64691c64e2b95b99491bd85442c>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <beb2b64691c64e2b95b99491bd85442c>:0 
Calling 'OnServerSave' on 'DisbandedTeamRestore v1.5.1' took 256ms

Changed Status from Pending to Can't Reproduce

If this still happens, I could add some debug lines to output/log to the console. I was never able to reproduce this error, no other server owner ever reported this bug.

the error happened in the oxide function "Oxide.Core.DataFileSystem.WriteObject" that I call,
I can debug any further into that code (not mine).