Failed to call hook 'OnUserRespawned' on plugin 'UFilter v5.1.1' (NullReferenceException: Object reference not set to an instance of an object)

I am getting this? I can provide more information if needed.

Could you provide the full log please?

Failed to call hook 'OnServerInitialized' on plugin 'UFilter v5.1.1' (JsonReaderException: After parsing a value an unexpected character was encountered: ". Path 'Profanities[30]', line 34, position 3.)
  at Newtonsoft.Json.JsonTextReader.ParsePostValue () [0x00179] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.JsonTextReader.Read () [0x0005a] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Linq.JContainer.ReadContentFrom (Newtonsoft.Json.JsonReader r, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x00226] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Linq.JContainer.ReadTokenFrom (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Linq.JsonLoadSettings options) [0x00030] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Linq.JArray.Load (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x0005f] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Linq.JArray.Load (Newtonsoft.Json.JsonReader reader) [0x00000] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Converters.HashSetConverter.ReadJson (Newtonsoft.Json.JsonReader reader, System.Type objectType, System.Object existingValue, Newtonsoft.Json.JsonSerializer serializer) [0x00041] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.DeserializeConvertable (Newtonsoft.Json.JsonConverter converter, Newtonsoft.Json.JsonReader reader, System.Type objectType, System.Object existingValue) [0x00055] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.SetPropertyValue (Newtonsoft.Json.Serialization.JsonProperty property, Newtonsoft.Json.JsonConverter propertyConverter, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerProperty, Newtonsoft.Json.JsonReader reader, System.Object target) [0x0004e] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject (System.Object newObject, Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, System.String id) [0x00267] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, System.Object existingValue) [0x0015c] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, System.Object existingValue) [0x0006d] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType, System.Boolean checkAdditionalContent) [0x000d9] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.JsonSerializer.DeserializeInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00053] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.JsonSerializer.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.JsonConvert.DeserializeObject (System.String value, System.Type type, Newtonsoft.Json.JsonSerializerSettings settings) [0x0002d] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Newtonsoft.Json.JsonConvert.DeserializeObject[T] (System.String value, Newtonsoft.Json.JsonSerializerSettings settings) [0x00000] in <2ae3f091decd4989b3c4d466e6eb5985>:0
  at Oxide.Core.Configuration.DynamicConfigFile.ReadObject[T] (System.String filename) [0x00028] in :0
  at Oxide.Core.DataFileSystem.ReadObject[T] (System.String name) [0x00021] in :0
  at Oxide.Plugins.UFilter.OnServerInitialized () [0x00011] in :0
  at Oxide.Plugins.UFilter.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000f5] in :0
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <3606d2af539c45e4b5c61658e6a8b307>:0
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in :0
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in :0

This is what it says on o.load UFilter, i get a bunch more errors after that such as the one you have seen above, but i think this is the main error.

Did you customize the oxide/data to add words, or add them via command?

I did add them via oxide data, not via the command.

Okay, so the error would make sense then; the data was not edited properly. When editing a json file, make sure to follow the format and verify using jsonlint.com if necessary.