Hashtable insert failed. Load factor too high -

Hi,
I am getting the following error occur on production HangfireSessionStorage.GetSimpleSessionStorage(Nullable`1 uniqueId)
I have two job queue servers running, with 20 threads per server. My app server can cope with up to 48 threads

"ExceptionType":"System.InvalidOperationException","ExceptionMessage":"Hashtable insert failed. Load factor too high. The most common cause is multiple threads writing to the Hashtable simultaneously.","ExceptionDetails":"System.InvalidOperationException: Hashtable insert failed. Load factor too high. The most common cause is multiple threads writing to the Hashtable simultaneously.\r\n   at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add)\r\n   at**strong text**

Has anyone come across this issue?