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When you map a network drive to a local share, the following warning message may be reported in the system event log:
Event ID: 3019 Source: MRxSmb Description: The redirector failed to determine the connection type.
This message can occur when NetBIOS over TCP/IP (NetBT) attempts to query the target device (in this case, the Loopback adapter) for network speed. The Loopback adapter, which does not handle speed negotiation, cannot negotiate the speed and the warning message is reported in the system event log.
This behavior only occurs with the TCP/IP protocol since TCP/IP is the only protocol that uses the Loopback adapter.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
This warning message is informational only and can be safely ignored.
This event is logged the first time you access a mapped drive and create a new session with the server. The message can also occur when you create a network connection to a share on your local computer. Therefore, the event can occur in any of the following situations:
The first time you access a mapped drive after you log on.
The first time you access the mapped drive after the computer resumes from hibernation mode.
The first time you access a local network share after the computer has been automatically disconnected from the mapped drive (by using the autodisconnect feature).
For additional information, click the article number below to view the article in the Microsoft Knowledge Base: