Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'

Check whether this helps or not but this is at the IIS level.. Also confirm which account you are using from your application.
https://weblogs.asp.net/nannettethacker/fix-for-login-failed-for-user-nt-authority-anonymous-logon

I have put some research and found something wrong with Kerberos.

So in your research you couldn't find the solution?

I usually don't like to try to solve an issue that I don't even know the exact error and the author is trying to point to some possible solution that nobody can assure is the correct issue.
Is like going to a doctor with a heart problem and told him that I made some researches and I think is something with my stomach.

No, I have not found any solution yet.

You can start to post here the last SQL Server error log file so we can analyze it.

as per above posts, it would be nice to get some extra details

and as per Raja Jegan R post - Start checking IIS  servers connecting your sql server
I'd check if you installed SSRS somewhere (same sql servers?) with
not configured Apps pool \etc AD service login ...


in SSMS try to run xp_readerrorlog to check details and originated server of this failed connection (you may see IP in the error)

Hi Thanks for the response. Yes, I have idea about the source server. I don't think so this is SSRS. We are receiving these error from 8 AM to 11:36 daily. Fix time.

On source server we have SQL Sentry only. When these error started 2 days before we have only update windows patches not on the same days. Now We have upgrade SQLSentry as well but no help.

<I have idea about the source server>
can you check if it runs IIS ?
if "yes', check what web sited you have there and use


Configure ASP.NET Impersonation Authentication (IIS 7)
https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc730708(v=ws.10)

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also check for possible linked server setup

https://social.technet.microsoft.com/Forums/ie/en-US/7e75b7d7-641f-4519-b5ea-9567985a2cce/linked-server-error-login-failed-for-user-nt-authorityanonymous-logon?forum=sqldatabaseengine

>> There was powershell job which was generate Login failure

Good catch, fix that job and it would fix your issue..

This question was solved by the author itself. My recommendation is to close it by accepting author's own comment or delete the question.

Since I've pointed the author to check for any scheduled jobs as part of this comment..

Can you kindly check for any jobs from SQL Server / Windows task scheduler or any other third party backup tools once..

I felt, I've guided the author towards identifying the solution and hence requested to close the question with my comment as answer..
If any moderators don't think so, then I don't have any objection in deleting this question..