after today's Halloween update

[Error] Failed to initialize plugin 'RaidAlarm v0.2.1'

Please check the oxide/logs for the full error.

[Error] Failed to initialize plugin 'RaidAlarm v0.2.1' (JsonReaderException: Error reading JArray from JsonReader. Current JsonReader item is not an array: StartObject. Path '', line 1, position 1.)
at Newtonsoft.Json.Linq.JArray.Load (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x0004c] 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.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 <9882f28dc2204b4dba514a9ad18f5042>:0
at Oxide.Core.DataFileSystem.ReadObject[T] (System.String name) [0x00021] in <9882f28dc2204b4dba514a9ad18f5042>:0
at Oxide.Plugins.RaidAlarm.ReadData () [0x00010] in <f4d3e94b44514895bd2197704b6dfb2e>:0
at Oxide.Plugins.RaidAlarm.Init () [0x00029] in <f4d3e94b44514895bd2197704b6dfb2e>:0
at Oxide.Plugins.RaidAlarm.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00108] in <f4d3e94b44514895bd2197704b6dfb2e>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <9882f28dc2204b4dba514a9ad18f5042>:0
at Oxide.Core.Plugins.CSPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x00043] in <9882f28dc2204b4dba514a9ad18f5042>:0

Looks like an error with your configuration file.

this is the config file for that plugin

{
"usePermissions": false
}

that's it it also filed on 3 servers all of which have been working fine before the update

Have you tried removing the config and reloading the plugin?

Resolved. Deleted data file and config and reloaded. Thanks for pointing me in the right direction Many Thanks Wulf.