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Updated the actual cause of the problem in my environment that fixed the issue
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AshMSport
AshMSport
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I had the same issue today on a site with Kerberos authentication. It started after I extended the web app using Powershell. I was seeingsaw the same errors in ULS logs as you have mentioned. For some reason the authentication mode for this web app changed from Kerberos to NTLM and the web app got converted to Classic mode. I switchedconverted it back to KerberosClaims mode and enabled kerberos and its back up. The ULS error 'Neither a claims user nor a claims user suffix' suggested something was wrong with claims mode. Checked it by running this command and the site loaded fineoutput was false: $WebAppName = "http://" $wa = get-SPWebApplication $WebAppName $wa.
 UseClaimsAuthentication Another strange thing is the authentication providers page for this web app has changedfalse Converted back to SP2010 style, I'm on SP2016.claims mode using this command: Convert-SPWebApplication -Identity yourWebAppUrl -To Claims -RetainPermissions [ -Force] Please verify the authentication settings ofcheck your web app and revert it to the previousapplication's authentication provider settings if you see any anomaly. Reference: https://technet.microsoft.com/en-us/library/gg251985.aspx

I had the same issue today on a site with Kerberos authentication. It started after I extended the web app using Powershell. I was seeing the same errors in ULS logs as you have mentioned. For some reason the authentication mode for this web app changed from Kerberos to NTLM. I switched it back to Kerberos and the site loaded fine.
  Another strange thing is the authentication providers page for this web app has changed to SP2010 style, I'm on SP2016. Please verify the authentication settings of your web app and revert it to the previous settings if you see any anomaly.

I had the same issue today on a site with Kerberos authentication. It started after I extended the web app using Powershell. I saw the same errors in ULS logs as you mentioned. For some reason the authentication mode for this web app changed from Kerberos to NTLM and the web app got converted to Classic mode. I converted it back to Claims mode and enabled kerberos and its back up. The ULS error 'Neither a claims user nor a claims user suffix' suggested something was wrong with claims mode. Checked it by running this command and the output was false: $WebAppName = "http://" $wa = get-SPWebApplication $WebAppName $wa.UseClaimsAuthentication false Converted back to claims mode using this command: Convert-SPWebApplication -Identity yourWebAppUrl -To Claims -RetainPermissions [ -Force] Please check your web application's authentication provider settings. Reference: https://technet.microsoft.com/en-us/library/gg251985.aspx

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AshMSport
AshMSport
  • 45
  • 2
  • 10

I had the same issue today on a site with Kerberos authentication. It started after I extended the web app using Powershell. I was seeing the same errors in ULS logs as you have mentioned. For some reason the authentication mode for this web app changed from Kerberos to NTLM. I switched it back to Kerberos and the site loaded fine.
Another strange thing is the authentication providers page for this web app has changed to SP2010 style, I'm on SP2016. Please verify the authentication settings of your web app and revert it to the previous settings if you see any anomaly.