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Microsoft KB Archive/254943

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Knowledge Base

XCON: Message Transfer Agent Stops Unexpectedly with Event ID 9405

Article ID: 254943

Article Last Modified on 10/26/2006


  • Microsoft Exchange Server 5.0 Standard Edition

This article was previously published under Q254943


The Microsoft Exchange Server message transfer agent (MTA) stops unexpectedly and an event similar to the following is logged in the application event log:

Event Id: 9405
Source: MSExchangeMTA
Type: Error
Category: Field Engineering
Description: An unexpected error has occurred which may cause the MTA to terminate.
Error: Out of Semaphores

When this problem occurs, no User.dmp file is created, even though the registry keys that force the MTA to stop (raise exception on fatal error and handle exceptions) are enabled.


This problem can occur because static variables are used to hold the semaphores, rather than dynamic variables.

The Calls.out file shows that the MTA terminates every time with the following

Thread 52 (01.091) owns semaphore 6601, created by (01.091).

where 6601 is the maximum count of semaphore.


A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Microsoft Exchange Server version 5.0 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:

Component: MTA

File name Version
Emsmta.exe 5.0.1462.10
Address.dll 5.0.1462.10
Emsrid.dll 5.0.1462.10
Mmiext.dll 5.0.1462.10
Mtacheck.exe 5.0.1462.10
Mtamsg.dll 5.0.1462.10
X400om.dll 5.0.1462.10
X400omv1.dll 5.0.1462.10
Dbserver.sch N/A N/A
Infoplog.cfg N/A
Infotlog.cfg N/A
Infoxlog.cfg N/A
P2.xv2 N/A
P3.tpl N/A
P772.tpl N/A


Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.0.

Additional query words: semaphores 9405

Keywords: kbbug kbexchange500presp3fix kbfix kbqfe KB254943