MaxMpxCt 2506 Error in Event Log

by Wayne Maples [Published on 20 April 2004 / Last Updated on 20 April 2004]

Windows 2000 system event log shows errors after startup:

Event : 2506
Source : Server
The value named MaxMpxCt in the server's Registry key LanmanServer \ Parameters was invalid. The value was ignored, and processing continued.

This is caused by the MaxMpxCt value having been set to less than 50 which is the legal minimum value. Unfortunately Norton's AntiVirus and perhaps other packages reset this value below the legal minimum. You can ignore the message but this is not recommended. There are reports that sporadic network errors were eliminated after MaxMpxCt was returned to its default. To fix, apply the following Windows 2000 registry hack:

Hive: HKEY_LOCAL_MACHINE
Key: SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
Name: MaxMpxCt
Type: REG_DWORD
Value: 50

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