• For host machine authentication failures, check that the credentials supplied to log in are valid and have sufficient permissions to collect WMI data and access files.
• For SQL Server instance authentication failures, check that the user name and password are correct and the login has the required permissions.

  For more information, see: Permissions required to monitor SQL Server.

  After an authorization error, by default SQL Monitor will not attempt to reconnect until you either change the credentials specified in SQL Monitor, or change the account permissions (in this case, you will need to click Retry connection on the Monitored Servers page). This prevents SQL Monitor from sending a potentially large number of failed login messages to your security log, and triggering Intrusion Detection System in the process.

  If the potential impact on your security log will not cause significant problems to your systems, you can change this default setting so that SQL Monitor will automatically attempt reconnection. See: Reconnecting automatically after monitoring stopped.

  Once the correct credentials are entered and authentication is successful, monitoring will resume and the Monitoring stopped ([host machine|SQL Server] credentials) alert will be marked as Ended.

One of the following reasons applies:

• The host machine or cluster node is not responding to WMI requests; either the machine name is incorrect or there is a network problem. A Machine unreachable alert is also raised, and a SQL Server instance unreachable alert is raised for each instance on the machine.
• The SQL Server service has been stopped or there is a problem with SQL connectivity. A SQL Server instance unreachable alert is also raised.

• Check that you have entered the server name correctly, and that your machine is not behind a firewall.
• Click Show log and check the Exception and Exception message columns displayed in the table of data collection events to determine the specific problem.

  For more information, see: What to try if you hit connection problems.

An unknown application error has occurred.

If this problem occurs continuously for 2 minutes, a Monitoring error ([host machine|SQL Server] data collection) alert is also raised.

SQL Monitor cannot process some data collected from the host machine or cluster node. Possible reasons are:

• The performance counter library may be corrupt and needs rebuilding. For information about rebuilding your PerfMon library, see http://support.microsoft.com/kb/300956.
• A WMI provider may be corrupt and needs rebuilding. For information about troubleshooting WMI, see http://technet.microsoft.com/en-us/library/ff406382.aspx.
• You are running a 32-bit SQL Server instance on a 64-bit Windows machine, and some performance counter objects are not available. For more information, see this MSDN article on 64-bit Support.

One of the following reasons applies:

• Remote file access is not set up (hidden administrative shares should be enabled).
• One of the required services (WMI, RPC) is not started.
• There is a problem with SQL connectivity.

  If this problem occurs continuously for 2 minutes, a Monitoring error ([host machine|SQL Server] data collection) alert is also raised.

SQL Monitor will automatically retry the connection every few minutes. Click Show log and refer to the Exception and Exception message columns in the table of data collection events for information about the type of problem.

For more information, see: What to try if you hit connection problems.

Enter a serial number or allocate licenses on the Configuration > Licensing page. One license is required for each host machine or cluster node – this will license all SQL Server instances on the machine or node.

For more information, see: Licensing.

Go to the Configuration > Monitored servers page to check when the current maintenance window is due to end.

For more information, see: Suppressing alerts.