Outlook 2010 + Exchange 2010 keeps asking for credentials - Please Help!

Question

Hello All,
Recently after a Windows Update + restart of my Exchange Server I'm having an issue with Outlook 2010 where it continually asks for credentials. Every 5 minutes or so the credentials popup appears and either typing your password or clicking cancel will make
Outlook work as expected again until the next popup, frequency of popups is about 2-5 minutes give or take. I am using Exchange 2010 on Server 2008 R2 and aside from the popup everything is working as expected. This seems to be effecting almost all users.
Some things I've tried already include:
- Removing any saved credentials on computer
- Removing and recreating Outlook Mail Profiles
- Running "Set-AutodiscoverVirtualDirectory -Identity 'autodiscover (default Web site)' -WindowsAuthentication $true -BasicAuthentication $false" in shell to disable basic authentication for autodiscover
- Running "get-outlookanyhwere | set-outlookanywhere -ClientAuthenticationMethod NTLM -IISAuthenticationMethods NTLM" in shell to ensure that outlook anywhere and IIS are using NTLM authentication
- Ensuring that the OAB folder permissions are set to allow Authenticated Users to Read/Execute
Anyways, if anybody has additional suggestions for me I'd very much appreciate them. Many users are using the Web App for the time being (with no issues) since the credentials popup is too annoying for them.

Answer 1

So I made sure that all of my authentication methods match the settings you linked me and then recycled the app pool you mentioned but am still having the issue.
One thing I noticed is that if a user experiencing the problem types their password into the credentials popup it will keep popping up continuously but if they hit cancel it says "Needs Password" where it would normally say "Connected to Microsoft Exchange"
and if they simply click once where it says "Needs Password" then all of a sudden it switches to "Connected to Microsoft Exchange" again and they no longer see the popup until Outlook is restarted.
Just to verify I have the proper settings now this is what shell returns:
[PS] C:\Windows\system32>Get-WebServicesVirtualDirectory | fl *auth*
CertificateAuthentication     :
InternalAuthenticationMethods : {Ntlm, WindowsIntegrated, WSSecurity}
ExternalAuthenticationMethods : {Ntlm, WindowsIntegrated, WSSecurity}
LiveIdSpNegoAuthentication    : False
WSSecurityAuthentication      : True
LiveIdBasicAuthentication     : False
BasicAuthentication           : False
DigestAuthentication          : False
WindowsAuthentication         : True
[PS] C:\Windows\system32>Get-AutodiscoverVirtualDirectory | fl *auth*
InternalAuthenticationMethods : {Basic, Ntlm, WindowsIntegrated, WSSecurity}
ExternalAuthenticationMethods : {Basic, Ntlm, WindowsIntegrated, WSSecurity}
LiveIdSpNegoAuthentication    : False
WSSecurityAuthentication      : True
LiveIdBasicAuthentication     : False
BasicAuthentication           : True
DigestAuthentication          : False
WindowsAuthentication         : True
Do you have any additional suggestions that I can try? From what I can tell my authentication methods all match the default settings now.
Edit: As soon as I changed EWA to just Basic Authentication as it says in the linked default settings I would get an error when trying to browse to the EWA that said "Outlook failed to initialize" and re-adding the Windows Authentication, then running iisreset
fixed the issue. Therefore EWA is the only service with non-default authentication methods now.