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I am a DBA with local sysadmin rights, and sysadmin rights on the SQL instance. Up until recently, i have been able to connect to a SQL Instance without issue.

All i am trying to do is connect to a SQL Instance using SSMS. Nothing fancy here - just normal login with Windows Authentication. Although this also occurs if using SQL Authentication.

Now i am getting an error message "User does not have permission to perform this action (Error 15427)".

My colleagues whom are also DBA's receive this same error. And the default SQL 'sa' account also receives this error.

I have never seen something like this before and am having difficulty finding helpful responses as they all seem to be focusing on the error number rather than the symptoms i am experiencing.

I can confirm that all Protocols are enabled and ordered as per our environment, and i can confirm that there have been no changes to this SQL Instance (that i am aware of). I can confirm the SQL Services are running and that permissions for the account running it have not changed (it is a gMSA).

The saving grace is that this is in our Test environment so no Production data is at risk here. So i also have a great deal of flexibility in things i can try to resolve.

Is someone able to please help me figure out what is going on here? Happy to provide further details if required,

SQL Server: 2016, Version: 13.0.6435.1, Edition: Developer, Product Level: SP3,

Cheers!

Update - further testing/checks

We have a user who is NOT a DBA. They are in an AD group that has read/write on a couple of DB's. They are able to connect to this SQL Instance. If i use their same machine, i am unable to connect to this SQL Instance.

I can connect using other SQL Logins that DO NOT have sysadmin. If i use a SQL Login that DOES have sysadmin, i cannot connect.

It seems like any login with sysadmin privileges is unable to connect??

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    Please clarify: is there or is there not a logon trigger? Commented Jun 10 at 10:16

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User does not have permission to perform this action (Error 15427).

These are two different items. Error 15427 states, "You must specify a provider name for unknown product '%ls'" which can happen when creating a new linked server. The other error seems to indicate a lack of permissions, which would seem odd given sa being used, as permission checks are skipped.

I have never seen something like this before and am having difficulty finding helpful responses as they all seem to be focusing on the error number rather than the symptoms i am experiencing.

Generally, when you get an error with a number you base your investigation off the error and not other symptoms.

The error is typically seen with linked servers setup improperly or someone attempting to dynamically setup a linked server improperly. Linked servers have nothing to do with logon events or logins, the only things that execute at logon are logon triggers, so it would make sense to start there and look for any that exist, then disable them.

To accomplish the above you'll want to start SQL Server in minimal configuration mode (-f) or single user mode (-m) and connect. This should bypass any logon triggers or other items. Check to logon triggers or other startup stored procedures and disable them. Restart the instance normally and try to log on.

If you still can't properly connect, take an etw trace with wpr -start cpu then repro the issue and save the trace with wpr -stop c:\some\file.etl. Make that file available and update the question with a link to the data.

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  • i cannot explain this but for some reason i am now able to connect outside of single user mode. ETW trace shows issue started on 1st May when Windows Updates were scheduled to roll out. I found that these updates were all stuck downloading or errored. I disabled the proxy (we have some proxy GPO) to ensure the server could connect to the internet to download the updates. Now i can connect to SQL with a sysadmin account. It makes no sense. But the issue appears to be resolved with no clear solution or cause. Commented Jun 10 at 3:09

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