Knowledge Base

Mapped Drive Connection to Network Share May Be Lost

Article ID: 297684

Article Last Modified on 12/3/2007

APPLIES TO

Microsoft Windows Server 2003, Standard Edition (32-bit x86)
Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
Microsoft Windows 2000 Server
Microsoft Windows 2000 Professional Edition
Microsoft Windows Small Business Server 2003 Premium Edition
Microsoft Windows Small Business Server 2003 Standard Edition

This article was previously published under Q297684

SYMPTOMS

On a computer that runs one of the versions of Windows that is listed at the beginning of this article, if you map a drive to a network share, the mapped drive may be disconnected after a regular interval of inactivity, and Windows Explorer may display a red "X" on the icon of the mapped drive. However, if you try to access or browse the mapped drive, it reconnects quickly. This behavior occurs if the network share computer runs Microsoft Windows NT 4.0, Windows 2000, or Windows Server 2003.

CAUSE

This behavior occurs because Windows NT Server 4.0, Windows 2000 Server, and Windows Server 2003 can drop idle connections after a specified time-out period (by default, 15 minutes) to prevent wasting server resources on unused sessions. The connection can be re-established very quickly, if required.

RESOLUTION

To resolve this behavior, change the default time-out period on the shared network computer. To do this, use one of the following methods.

NOTE: You cannot change the default time-out period for Microsoft Windows 95-based computers and Microsoft Windows 98-based computers that have shared resources.

Registry Editor

NOTE: You cannot use this method to turn off the autodisconnect feature of the Server service. You can only use this method to change the default time-out period for the autodisconnect feature. WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

Use Registry Editor to increase the default time-out period. To do this, follow these steps, and then quit Registry Editor:

Click Start, click Run, type regedit (Windows 2000 or Windows Server 2003) or type regedt32 (Windows NT 4.0), and then click OK.
Locate and then click the following key in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters

NOTE: The client side session is automatically disconnected when the idling time lasts more than the duration that is set in KeepConn. For this reason, the session is disconnected according to the less set duration value between AutoDisConnect and KeepConn. To modify the timeout duration in the client side during a UNC connection, specify the arbitrary time in KeepConn from registry value.
Locate and then click the following key in the registry: '

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Service\lanmanworkstation\parameters

Value: KeepConn
Data type : REG_DWORD
Range : 1 to 65535 (sec)

Default value: 600 sec = 10 mins
In the right pane, click the autodisconnect value, and then on the Edit menu, click Modify. If the autodisconnect value does not exist, follow these steps:
1. On the Edit menu, point to New, and then click REG_DWORD.
2. Type autodisconnect, and then press ENTER.
On the Edit menu, click Modify.
Click Hexadecimal.
In the Value data box, type ffffffff, and then click OK.

Command Line

NOTE: If you use this method, you may turn off the autotuning feature for the Server service.

To change the default time-out period for the autodisconnect feature of the Server service, open a command prompt, type the following line, and then press ENTER

net config server /autodisconnect:number

where number is the number of minutes that you want the server to wait before it disconnects a mapped network drive. The maximum value for this command is 65,535.

NOTE: If you set the autodisconnect value to 0 (zero), the autodisconnect feature is not turned off, and the Server service disconnects mapped network drives after only a few seconds of idle time.

To turn off the autodisconnect feature, open a command prompt, type the following line, and then press ENTER:

net config server /autodisconnect:-1

MORE INFORMATION

Some earlier programs may not save files or access data when the drive is disconnected. However, these programs function normally before the drive is disconnected.

For additional information about how to increase the default time-out period, click the following article numbers to view the articles in the Microsoft Knowledge Base:

138365 How Autodisconnect Works in Windows NT and Windows 2000

128167 Server Service Configuration and Tuning

Keywords: kbenv kbprb KB297684

Microsoft KB Archive/297684

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