I'm getting this error when a player connects or i try to sync roles

Web request callback raised an exception (JsonReaderException: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.) at Newtonsoft.Json.JsonTextReader.ParseValue () [0x002b3] in <45c13f2b01574d8b82248736e42013a4>:0
at Newtonsoft.Json.JsonTextReader.Read () [0x0004c] in <45c13f2b01574d8b82248736e42013a4>:0
at Newtonsoft.Json.Linq.JObject.Load (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x00013] in <45c13f2b01574d8b82248736e42013a4>:0
at Newtonsoft.Json.Linq.JObject.Parse (System.String json, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x0000c] in <45c13f2b01574d8b82248736e42013a4>:0
at Newtonsoft.Json.Linq.JObject.Parse (System.String json) [0x00000] in <45c13f2b01574d8b82248736e42013a4>:0
at Oxide.Plugins.Ember.<PostUsers>m__0 (System.Int32 code, System.String response) [0x00029] in <1f6fb6571f334e1cb627aad7c253d2b4>:0
at Oxide.Core.Libraries.WebRequests+WebRequest.<OnComplete>b__42_0 () [0x00034] in <ec05e0208c9149bba43236ca58fea105>:0

Hey,
seems like the response contains HTML tags. That might happen if the URL specified in the plugin's configuration isn't valid / doesn't point to an Ember instance. One thing to check for is if the URL contains a trailing slash - those aren't automatically parsed away yet.