Login failed for user 'domain\Administrator'. (Microsoft SQL Server, Error: 18456) On my newly installed SQL Server 2014, I get the following error when trying to connect to the SQL Server:

2015-05-13 12:09:38.40 Logon   Error: 18456, Severity: 14, State: 5.
2015-05-13 12:09:38.40 Logon   Login failed for user 'INTRA\Administrator'.
Reason: could not find a login matching the name provided. [CLIENT: &lt;local machine&gt;]


I reinstalled the sql server three times.

The user for which the login fails is the AD user with which I am logged into the server itself. When logging in via SSMS, I don't have to give any credentials (it is auto-filled), so this can't be a typo error.

How can I resolve this issue?

PS: I also had problems with the SSL cert which are already resolved, so the underlying problem may be bigger.
I reinstalled the sql server three times.


During the installation you are asked what users to be added as instance administrators. You should add yourself. You probably added the built-in Administrators group and now you're running a LUA process and had lost the admin token and cannot access the instance. If yes, then is simply a mater of running the client process elevated ('Run as administrator').

If you have omitted to add the built-in Administrators group as SQL instance admins then you must follow the steps described at Connect to SQL Server When System Administrators Are Locked Out.