here's the whole very long error:
Failed to initialize plugin 'BetterChat v5.2.14' (JsonReaderException: Unexpected character encountered while parsing number: I. Path '[15].Priority', line 349, position 17.)
at Newtonsoft.Json.JsonTextReader.ReadNumberIntoBuffer () [0x0013f] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonTextReader.ParseNumber (Newtonsoft.Json.ReadType readType) [0x0001b] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonTextReader.ReadNumberValue (Newtonsoft.Json.ReadType readType) [0x00203] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonTextReader.ReadAsInt32 () [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadForType (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonContract contract, System.Boolean hasConverter) [0x0004a] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ResolvePropertyAndCreatorValues (Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty containerProperty, Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x000dc] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObjectUsingCreatorWithParameters (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty containerProperty, Newtonsoft.Json.Serialization.ObjectConstructor`1[T] creator, System.String id) [0x000b7] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateNewObject (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonObjectContract objectContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, Newtonsoft.Json.Serialization.JsonProperty containerProperty, System.String id, System.Boolean& createdFromNonDefaultCreator) [0x0008c] in <271c58b7a8684db5a2c92be17a81f252>: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) [0x00143] in <271c58b7a8684db5a2c92be17a81f252>: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 <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateList (System.Collections.IList list, Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonArrayContract contract, Newtonsoft.Json.Serialization.JsonProperty containerProperty, System.String id) [0x0016f] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateList (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, System.Object existingValue, System.String id) [0x000dc] in <271c58b7a8684db5a2c92be17a81f252>: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) [0x0007f] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType, System.Boolean checkAdditionalContent) [0x000d9] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonSerializer.DeserializeInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00053] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonSerializer.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonConvert.DeserializeObject (System.String value, System.Type type, Newtonsoft.Json.JsonSerializerSettings settings) [0x0002d] in <271c58b7a8684db5a2c92be17a81f252>:0
at Newtonsoft.Json.JsonConvert.DeserializeObject[T] (System.String value, Newtonsoft.Json.JsonSerializerSettings settings) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0
at Oxide.Core.Configuration.DynamicConfigFile.ReadObject[T] (System.String filename) [0x00028] in <beb2b64691c64e2b95b99491bd85442c>:0
at Oxide.Core.DataFileSystem.ReadObject[T] (System.String name) [0x00021] in <beb2b64691c64e2b95b99491bd85442c>:0
at Oxide.Plugins.BetterChat.LoadData[T] (T& data, System.String filename) [0x00016] in <5636fba45c3c42eeb8afb6246e0b397c>:0
at Oxide.Plugins.BetterChat.Loaded () [0x00006] in <5636fba45c3c42eeb8afb6246e0b397c>:0
at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00038] in <5636fba45c3c42eeb8afb6246e0b397c>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <206a0f2c6ee141f38e2ad549cde44d70>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <beb2b64691c64e2b95b99491bd85442c>:0
at Oxide.Plugins.CSharpPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x000cf] in <206a0f2c6ee141f38e2ad549cde44d70>:0

It unloads itself after the error, so it's not running at all.
An update would be very helpful and much appreciated.  Umod says it's been over a year since there was one and it seems like one is very much needed at this point.

Nuts.  BetterChat is used by a ton of our other plugins, so no titles are showing from /ranks or from our custom titles either.  Of course not; the plugin unloads itself because of the error.  I hope sincerely that this gets updated very soon, it's one of the essential plugins on our server.

We are having the same issue.  Plug wont work.

This plugin is used by a ton of our other plugins.  We really need an update badly.  I hope the developer is paying attention to his support pages.

Plugin works fine, looks like your datafile might be corrupted. Unload the plugin, delete the file from the data folder (after saving a backup!) and reload the plugin.

Thank you MrBlue.  A line in the datafile DID get changed and after fixing it, things are working again.

Merged post

Redspyder,  type plugins in console and it will tell you which line needs fixed.

Redspyder

Nuts.  BetterChat is used by a ton of our other plugins, so no titles are showing from /ranks or from our custom titles either.  Of course not; the plugin unloads itself because of the error.  I hope sincerely that this gets updated very soon, it's one of the essential plugins on our server.

This line tells you where the data file error is, just correct the error and it should be fine

Failed to initialize plugin 'BetterChat v5.2.14' (JsonReaderException: Unexpected character encountered while parsing number: I. Path '[15].Priority', line 349, position 17.)