Started getting the following error today about 15 min after restart.. No changes to any files and has been working flawless for more then 6 months

An exception was thrown whilst validating your secret key: Error reading JObject from JsonReader. Path '', line 0, position 0.

11/08 07:38:45 | [Tebex Donate] Associated response:

11/08 07:38:45 | [Tebex Donate] at Newtonsoft.Json.Linq.JObject.Load (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x00026] in <2ae3f091decd4989b3c4d466e6eb5985>:0
at Newtonsoft.Json.Linq.JObject.Parse (System.String json, Newtonsoft.Json.Linq.JsonLoadSettings settings) [0x0000c] in <2ae3f091decd4989b3c4d466e6eb5985>:0
at Newtonsoft.Json.Linq.JObject.Parse (System.String json) [0x00000] in <2ae3f091decd4989b3c4d466e6eb5985>:0
at Oxide.Plugins.TebexDonate+<FetchStoreInformation>c__AnonStorey1.<>m__1 (System.Int32 code, System.String response) [0x00006] in <b6a9782f9dbe4eb9b23b254104846620>:0​

Same error for me.

[Tebex Donate] An exception was thrown whilst validating your secret key: Error reading JObject from JsonReader. Path '', line 0, position 0.

same on all of my servers