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Article ID: 838659 - Last Review: August 29, 2007 - Revision: 3.1

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When you use speech engines to do recognition or synthesis, you can save the CurrentUserLexicon file on your local hard disk to store additional words. Sometimes, the CurrentUserLexicon file can become corrupted. When this happens, the speech recognition (SR) engine and the text-to-speech (TTS) engine do not work. This article describes possible causes and fixes the problem with a hotfix file.


The speech recognition (SR) engine and the text-to-speech (TTS) engine do not work in any applications. When you open Speech Control Panel, you may receive the following message:
The requested task cannot be carried out because the necessary speech engine could not be created. Please select a different engine and/or a different audio device.


Currently, the specific cause of the problem is not known. However, the following are possible causes:
  • An incorrectly configured audio device
  • A corrupted recording profile
  • A corrupted user lexicon database (CurrentUserLexicon)
To determine whether CurrentUserLexicon is corrupted, use a hexadecimal editor to open the .dat file that is located in the following folder:
\Documents and Settings\UserName\Application Data\Microsoft\Speech\Files\UserLexicons
If the file contains only 0x00 byte values and contains no other data values, the user lexicon database has likely been corrupted.


To work around this problem, delete the corrupted user lexicon file. The system then re-creates an empty version of the file. After this, the SR engine and the TTS engine can function.

Note If you delete the user lexicon file, you lose any user-specific vocabulary that was previously added.

To delete the user lexicon file, delete the following folder:
\Documents and Settings\UserName\Application Data\Microsoft\Speech\Files\UserLexicons


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 hotfix has the file attributes (or later file attributes) 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.
Date         Time   Version     Size     File name
   09-Mar-2004  22:26  6.0.1518.0  696,320  Sapi.dll


Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section of this article.

  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
  • Microsoft Speech Software Development Kit (SDK) 5.1
kbautohotfix kbfix kbqfe kbhotfixserver KB838659
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