Login failed for user <null> usually means that on the SQL box, the user
account could not be found in the local security database or in the domain
controller's user database.
For example, on machine1 I log in as machine1\user1. Then I try to log into
SQL on machine2. On machine2 SQL takes the SID of the user and calls
LookupAccountSID API. This attempts to convert the SID to the user name.
LookupAccountSID first looks in local security database on machine2, and
does not find machine1\User1, then looks on domain controller, and still
does not find the SID.
So in general this points to problems with the user account. Perhaps the
user has the same account name defined on their local machine and when they
log in they don't realize that they are logging in as the local User1 versus
the domain User1. Go to the problematic machine and check the user
accounts. If this does not work, perhaps have the domain admin drop the
user account and recreate it.
Matt
[quoted text, click to view] "Sue Hoegemeier" <Sue_H@nomail.please> wrote in message
news:jd4sr0ds5vna1pc5ph4ri66j5hmri6d51p@4ax.com...
> It really depends on where the process is failing. You would
> want to check the event logs on the PC having the problems
> connecting. Check for any network related issues or
> problems. Make sure that PC is contacting the domain
> controllers without any problems and that they are
> successfully logging into the network.
>
> -Sue
>
> On Mon, 13 Dec 2004 08:25:02 -0800, "JC"
> <JC@discussions.microsoft.com> wrote:
>
>>Rand, what about a solution or al least pointing to one?
>>
>>"Rand Boyd [MSFT]" wrote:
>>
>>> This is always an authentication problem somewhere. The null indicates
>>> that
>>> user cannot be validated and a null is being passsed to SQL Server.
>>>
>>> Rand
>>> This posting is provided "as is" with no warranties and confers no
>>> rights.
>>>
>>>
>
