Autodiscover Error in Windows UWP app

[somasundarambk]

Hello, The UWP package we own throws this exception (below).
The call to DnsNativeMethods.FreeDnsQueryResults(queryResultsPtr); is called without a try catch around it and this stops further processing of auto discovery.

 0x80131522 System.TypeLoadException: Unresolved P/Invoke method 'dnsapi.dll!DnsRecordListFree' from this method. Please look for this method in build warnings for more details. 

	 at Microsoft.Exchange.WebServices.Dns.DnsNativeMethods.DnsRecordListFree(IntPtr, DnsNativeMethods.FreeType) + 0x2d
	 at Microsoft.Exchange.WebServices.Dns.DnsNativeMethods.FreeDnsQueryResults(IntPtr) + 0x8
	 at Microsoft.Exchange.WebServices.Dns.DnsClient.DnsQuery[T](String, IPAddress) + 0x2c0
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverDnsClient.FindBestMatchingSrvRecord(String) + 0x8d
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverDnsClient.FindAutodiscoverHostFromSrv(String) + 0x24
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetRedirectionUrlFromDnsSrvRecord(String) + 0x3a
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetSettings[TGetSettingsResponseCollection, TSettingName](List`1, List`1, Nullable`1, AutodiscoverService.GetSettingsMethod`2, Func`1) + 0x381
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetUserSettings(List`1, List`1) + 0xcb
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.InternalGetSoapUserSettings(String, List`1) + 0x12a
	 at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetUserSettings(String, UserSettingName[]) + 0x5a
	 at Microsoft.Exchange.WebServices.Data.ExchangeService.GetAutodiscoverUrl(String, ExchangeVersion, AutodiscoverRedirectionUrlValidationCallback) + 0x87
	 at Microsoft.Exchange.WebServices.Data.ExchangeService.AutodiscoverUrl(String, AutodiscoverRedirectionUrlValidationCallback) + 0x34

[blakepell]

So I recently ran into this also when moving from the full framework version to this version. The short of it was, I forked the original Microsoft repo and converted it to .NET Standard 2 (didn't take much time and there were few hiccups, just added a few NuGets and removed one System.Web using). In the end though I tried to make AutoDiscovery work and couldn't. I manually entered the URL (which you'll have to find, it will be unique to your environment possibly):

var service = new ExchangeService(ExchangeVersion.Exchange2013_SP1)
{
    Credentials = new WebCredentials(username, password, domain)
};

// To future me, when this URL breaks at some point because it will, it has to be 
// updated to whatever the URL is on the new server.  Try to see if AutoDiscovery is working 
// again and also check that ExchangeVersion is still correct.
service.Url = new Uri(exchangeUrl);
service.EnableScpLookup = false;
service.Timeout = (1000 * 60) * 5;  // 5 Minutes

Not ideal but sometimes you have to get stuff done.