When you try to save a file such as a Microsoft Excel workbook that you opened by using a universal naming convention (UNC) path, you may receive an error message that is similar to one of the following: Event Viewer may contain the following event:

Event Type: Information
Event Source: Application Popup
Event Category: None
Event ID: 26
User: N/A
Description: Application popup: Windows - Delayed Write Failed : Windows was unable to save all the data for the file name_of_the_file_you_want_to_save. The data has been lost. This error may be caused by a failure of your computer hardware or network connection. Please try to save this file elsewhere. For more information, see Help and Support Center at http://support.microsoft.com.

This problem occurs when the redirector flushes the contents of the file, and writes to a file handle with read-only access instead of to a file handle with write access. When the redirector received an opportunistic lock break to none, it purged the cache for the file, but did not uninitialize the cache for the file. The redirector also needed to purge and uninitialize when the set end of file occurs because the opportunistic lock break is asynchronous. Because it did not uninitialize the cache for the file, it wrote to the incorrect file handle.

Service pack information

To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Windows XP SP1, Windows XP Tablet PC Edition

Windows XP 64-Bit Edition

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: To work around this problem, disable opportunistic locking on the file server:

1. Click Start, and then click Run.
2. In the Open box, type regedit, and then press ENTER.
3. In Registry Editor, locate the following subkey in the registry:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Services\LanmanServer\Parameters
4. In the right pane, click EnableOplocks, and then press ENTER.
5. In the Value data box, type 0, and then press ENTER.
6. Quit Registry Editor.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Microsoft Windows XP Service Pack 2.

For additional information about opportunistic locking, click the following article number to view the article in the Microsoft Knowledge Base: A trace of this problem shows that the file is opened at least two times, and shows the system improperly writing to the read-only file handle. A trace that shows this problem is similar to the following:Note The process identifier (PID) of 0xFEFF in frame 585 represents the client system process that is using the read-only file handle. It does not show the client program writing the data to disk.