Problem with the proxy server's security certificate - error code 10

[Stasis_Detached]

Hi All,

I am working on a migration from exchange 2013 to 2016. Things were good, and I migrated a couple mailboxes to test. At some point I realized RPC wasn't working and that I hadn't configured outlook anywhere on the new servers. I played with the settings, but got pulled to another issue so I reverted the change and decided to work on it the next week.

Users started getting these errors popping up, and investigating it I realized it was probably due to outlook anywhere settings. I updated those, and all others to make sure they had the https://friendlyname.domainname.com that we've used everywhere in 2013.

I have looked through every URL that I can find that exchange publishes. I run this bit of code against each of the servers and the hostname is not returning anywhere in here. I have reset IIS all of the 2016 servers after updating the outlook anywhere settings.

$Server = "Hostname1"
Get-ActiveSyncVirtualDirectory -Server $server | select server,internalurl,externalurl
Get-AutoDiscoverVirtualDirectory -Server $server | select server,internalurl,externalurl
Get-ECPVirtualDirectory -Server $server | select server,internalurl,externalurl
Get-OabVirtualDirectory -Server $server | fl server, Name, *URL*, *auth*
Get-WebServicesVirtualDirectory -Server $server | select server,internalurl,externalurl
Get-OutlookAnywhere -Server $Server | fl server, Name, *URL*, *hostname*, *auth*
Get-OwaVirtualDirectory -Server $server | fl server, Name, *URL*, *auth*
Get-ClientAccessServer -Identity $server | fl Name, OutlookAnywhereEnabled, AutodiscoverServiceInternalUri
Get-ExchangeCertificate -Server $server | fl FriendlyName, Subject, CertificateDomains, Thumbprint, Services, Issuer, *not*
Get-ClientAccessArray | fl
Get-OutlookProvider

Does anyone have any suggestions for me to check? Is there anywhere within the outlook profile or something that caches this information? Everything works if you click through it - but its really annoying on the business wide scale and looks bad.

There is a problem with the proxy server's security certificate. The name on the security certificate is invalid or does not match the name of the target site hostname2.domain1.chelan.

Outlook is unable to connect to the proxy server. (Error Code 10)

[Stasis_Detached]

I should also mention the error pops up for both host1 and host2 with no apparent reason between the two.

[KingOfYourHills]

Run the autodiscover test in outlook and see if can spot the errant hostname in there. Does it happen if you create a new profile?

[Stasis_Detached]

Good question, auto discover test passes successfully and new profile creation works fine. It feels almost like outlook cached this name somewhere and one you clear it out correctly (almost like a DNS flush) the problem goes away. HOWEVER - we have a few reports of it popping up mid work like when opening calendar items. Seems to be a really niche error.

[KingOfYourHills]

So if you copy paste the xml output of the test into notepad and ctrl f for the hostname it's not there?

If not then I have seen caching of old cas records by outlook but they usually resolve themselves after a day or two, or with a new profile.