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Folder Redirection fails with the error ERROR_SEM_TIMEOUT or the semaphore timeout period has expired

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This article helps fix an ERROR_SEM_TIMEOUT error that occurs when you find out the Folder Redirection policy isn't working on the client machine.

Applies to:   Windows 7 Service Pack 1
Original KB number:   2570355

Symptoms

You have a computer running Windows Vista or Windows 7 in a domain. You find out the Folder Redirection policy is not working on the client machine. When you look at the event log, you see the following event logged:

Log Name: Application
Source: Microsoft-Windows-Folder Redirection
Date: <Date & Time>
Event ID: 502
Task Category: None
Level: Error
Keywords:
User: <User Name>
Computer: <Computer Name>
Description:
Failed to apply policy and redirect folder "Documents" to "<a network share>".
Redirection options=0x1219.
The following error occurred: "Failed to copy files from "C:\Users\<UserName>\Documents" to "<a network share>".
Error details: "The semaphore timeout period has expired".

Cause

This issue is caused by a file name or path name containing more than 259 characters.

Resolution

Use the Process Monitor tool to identify the problematic file with long path name, and then delete it or reduce its path name.

More information

Process Monitor is an advanced monitoring tool for Windows that shows real-time file system, Registry, and process/thread activity. Refer to the following web page for more information about this tool:

Process Monitor v3.60

The following two errors share the same error number, and this is the reason why the error message "The semaphore timeout period has expired" is displayed.

Error Number - Error Code - Meaning
0x79 - ERROR_SEM_TIMEOUT - The semaphore timeout period has expired.
0x79 - DE_PATHTOODEEP - The source or destination path exceeded or would exceed MAX_PATH.

Refer to the following web pages for more information about the two errors: