NullReferenceException - LookupClient.ProcessResponseMessage

[Silvenga]

I haven't been able to reproduce this on demand, it only occurs under heavy load.

DnsClient.DnsResponseException: Query 43835 => pull-cmaf-f5.tiktokcdn.com IN A on 10.43.37.252:53 failed with an error.
---> System.NullReferenceException: Object reference not set to an instance of an object.
  at DnsClient.LookupClient.ProcessResponseMessage(LookupClientAudit audit, DnsRequestMessage request, DnsResponseMessage response, DnsQuerySettings settings, NameServer nameServer, DnsMessageHandleType handleType, Int32 serverCount, Boolean isLastServer, HandleError& handleError)
  at DnsClient.LookupClient.ResolveQueryAsync(IReadOnlyList`1 servers, DnsQuerySettings settings, DnsMessageHandler handler, DnsRequestMessage request, LookupClientAudit audit, CancellationToken cancellationToken)
  --- End of inner exception stack trace ---
  at DnsClient.LookupClient.ResolveQueryAsync(IReadOnlyList`1 servers, DnsQuerySettings settings, DnsMessageHandler handler, DnsRequestMessage request, LookupClientAudit audit, CancellationToken cancellationToken)
  at DnsClient.LookupClient.QueryInternalAsync(DnsQuestion question, DnsQuerySettings queryOptions, IReadOnlyCollection`1 servers, CancellationToken cancellationToken)

The DnsResponseException had:

Code: Unassigned
DnsError: 'Unknown Error'

10.43.37.252:53 is an unbound server acting in recursive mode with rate-limiting disabled.

[Silvenga]

Retrying does allow the request to succeed the second time most of the time, Trace logging doesn't have anything useful. Nothing obvious jumps out in the code. 🤔

[MichaCo]

Hi, thanks for the report.

Yeah, it at least shouldn't throw a null reference exceptions. I'll take a look

[MichaCo]

The occurrence of a NullReferenceException should be fixed in 1.6. Not 100% sure though so let me know if that still happens