Connecting to Plex

I updated Plex to version 0.9.12.3, and now when Sonarr tries notify Plex I get an error message.

Message:

Unable to connect to Plex Server: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.

Exception:

Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.
at Newtonsoft.Json.JsonTextReader.ParseValue () [0x00000] in <filename unknown>:0 
at Newtonsoft.Json.JsonTextReader.ReadInternal () [0x00000] in <filename unknown>:0 
at Newtonsoft.Json.JsonTextReader.Read () [0x00000] in <filename unknown>:0 
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadForType (Newtonsoft.Json.JsonReader reader,       Newtonsoft.Json.Serialization.JsonContract contract, Boolean hasConverter) [0x00000] in <filename unknown>:0 
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType, Boolean checkAdditionalContent) [0x00000] in <filename unknown>:0 

I am running Sonarr 2.0.0.3212 on Ubuntu 14.04

Have you set your username and password for Plex in Sonarr? Looks like an authentication issue.

Thanks that worked. I already had all the information in there, so I thought it was fine. I reentered it and it works fine now.