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IntroductionThe Microsoft Jet database engine is used by a wide variety of applications so it is possible that an application installation, or, more likely, an application uninstallation could adversely affect other applications on your computer. This article details steps you can take to make sure that Microsoft Jet is correctly installed on your computer.
The document is divided into three sections, (a) Troubleshooting the Access Method, which covers making sure the DAO, ADO, and ODBC drivers are installed correctly, (b) Troubleshooting Microsoft Jet, which covers the Jet DLLs and registry settings, and (c) Resource Data, which lists registry keys that would make the body of the article difficult to read.
Please see the following Microsoft Knowledge Base article for a continuation of this article, which includes Part C, the Resource Data:
Troubleshooting the Access MethodBefore troubleshooting the Jet installation, you need to make sure that the access method is correctly installed. The following sections cover DAO, ODBC, and ADO.
Data Access Objects (DAO)DAO is the most common Jet access method. The following steps can be used to make sure that it is properly installed:
- Make sure you have the following file:
NOTE: The drive letter may be different if your copy of Windows is installed on a drive other than drive C:.
C:\Program Files\Common Files\Microsoft Shared\Dao\Dao350.dll
- If your project references the Microsoft DAO 2.5/3.5 (or 3.51) Compatibility Library instead of the Microsoft DAO 3.5 (or 3.51) Library, then you need to make sure the following file is installed:
C:\Program Files\Common Files\Microsoft Shared\Dao\Dao2535.tlb
- You need to make sure that the registry keys for DAO exist. The registry keys are listed in the Microsoft DAO Registry Settings section later in this article. Use the RegEdit program to verify that the registry keys exist. If the registry keys are missing or pointing to a nonexistent file, you can manually unregister and re-register the Dao350.dll file by running the following two commands from the Windows Start button, and then select Run or from the MS/DOS command prompt use this command:
Note that the earlier two commands have a line break for readability. You should run each command on one continuous line.
"C:\Program Files\Common Files\Microsoft Shared\Dao\Dao350.dll"
"C:\Program Files\Common Files\Microsoft Shared\Dao\Dao350.dll"
Alternately, you can edit the registry directly. Instructions for applying the values through a .reg file are given in the Microsoft DAO Registry Settings section.
- Once the file and registry settings are in place, you can test the DAO installation through code. Make a reference to the Microsoft DAO 3.5 (or 3.51) Library in your project and run the following statement:If the statement works, yet your application still fails, you should continue with the "Troubleshooting Microsoft Jet" section.
If the preceding test code causes this run-time error message:'429': ActiveX component can't create object.check to see if the DAO design-time license key exists on your computer. The following three lines may be saved to a file with the .reg extension and imported into the registry through the RegEdit program:
- If the code fails with an access violation, some of the support files may be out of date, typically:
The latest version of these files can be obtained by installing the latest version of:
NOTE: Installing this file may overwrite the Microsoft Access ODBC drivers as outlined in the following section. If you have programs that use these drivers, you should be cautious about upgrading them.
- Occasionally, an access violation may result from a mismatch between the version of Dao350.dll and some of the other Jet or support DLLs. For example, if you have a 3.50 version of Dao350.dll and Jet 3.51, you might have problems. Upgrading to a 3.51 version of Dao350.dll might help.
Microsoft Access ODBC DriversInstalling Microsoft Access 2000, Microsoft Visual Basic 6.0 SP3, Microsoft Windows 2000, ADO 2.1 or later, and other products may break programs that use the Microsoft Access ODBC driver. These applications replace the Microsoft Jet 3.5 ODBC drivers with Microsoft Jet 4.0 ODBC drivers. These drivers have different capabilities and may cause your application to fail under certain circumstances. You can check the version numbers of the following files:
These files are located in your Windows\System (or Winnt\System32 for Windows NT) folder. The file version should start with 3.5 or 3.51.
If the version number starts with 4.0, then the following Microsoft Knowledge Base article deals specifically with this problem:
The article can also be used if the files do not exist at all. Once the drivers are in place, you should be able to view them in the ODBC Administrator in Control Panel (or Administrative Tools, if you are using Windows 2000), create DSNs to MDB and ISAM files, and compact a Microsoft Access database. If the article does not resolve the problem and you can use other ODBC drivers without experiencing a problem, continue to the Troubleshooting Microsoft Jet section.
ActiveX Data Objects (ADO)
- First verify that you can use ADO with a provider other than the OLEDB Provider for Microsoft Jet. If not, then you need to verify that ADO is properly installed and registered. The following Microsoft Knowledge Base article helps you to troubleshoot the Microsoft Data Access Components:232060 How To MDAC Setup Troubleshooting GuideAfter ADO is installed and working properly proceed with the following steps to verify that the OLEDB provider for Microsoft Jet is properly installed and registered.
- The OLEDB provider for Microsoft Jet 3.5 consists of the following two files:
Msjt4jlt.dll is Jet 3.52, a special version of Jet 3.5 specifically for ADO. It does not support linked files, stored queries, or the Installable ISAM drivers. It does rely on some of the other Jet 3.51 core files, specifically Msjter35.dll and Msjint35.dll, also located in the system directory.
C:\Windows\System\Msjt4jlt.dll (Winnt\System32 for Windows NT or Windows 2000)
C:\Program Files\Common Files\System\Ole Db\Msjtor35.dll
If these files do not exist, you can obtain them by downloading
MDAC 2.0from the following location on the Web, or from Visual Basic 6.0 (versions prior to SP3). MDAC 2.1 and later do not contain these files.
If you do not have MDAC 2.1 or later on your computer, you can download the MDAC 2.0 version of the MDAC_TYP.exe file and run it to install these components. This MDAC 2.0 version of the MDAC_TYP.EXE file can be found at the following location:http://microsoft.com/data/download_20300223.htmIf you do have a 2.1 or later version of MDAC on your computer, copy the MDAC 2.0 MDAC_TYP.exe file to a clean directory and run the following command:
mdac_typ.exe /c /t:C:\MDAC20
This extracts the files into the C:\Mdac20 folder without installing them on your system. You can then copy the Msjt4jlt.dll and Msjtor35.dll files from this location to the directories indicated below in the REGSVR32 commands.
- Register the files in the following order:
If these steps do not resolve the problem, continue with the Troubleshooting Microsoft Jet section.
Regsvr32.exe C:\Windows\System\Msjt4jlt.dll (Winnt\System32 for Windows NT or Windows 2000)
Regsvr32.exe "C:\Program Files\Common Files\System\Ole Db\Msjtor35.DLL"
Troubleshooting Microsoft JetIf you have reached this step, then you should be experiencing problems with Microsoft Access, the Microsoft Visual Basic data control, the VISDATA add-in, other applications, and your own DAO, RDO, and ADO code.
Core Jet Files
- In order for Microsoft Jet to operate, you need a minimum of the following files installed on your computer, all in the C:\Windows\System directory (Winnt\System32 for Windows NT or Windows 2000):
Expsrv.dll (this was introduced with Vbajet32.dll 6.x versions)
- The Microsoft Jet registry keys are given in the Microsoft Jet Registry Settings section at the end of the article. Verify the registry keys exist. If not, the section gives instructions on creating them through a .reg file.
- After completing these steps, you should be able to use Microsoft Jet to open Microsoft Jet 3.x database files. If you still have problems, some of the dependencies may be out of date. You can update them as detailed in the next section.
Jet DependenciesMicrosoft Jet has a number of file dependencies:
Older versions of the Oleaut32.dll file especially can be problematic. The Expsrv.dll file will not work properly with older versions. You can obtain the latest version of these DLLs by downloading the latest Microsoft Data Access Components from the Web. If you need the 3.5 version of the Microsoft Access ODBC drivers, you will have to restore them, as detailed in the Microsoft Access ODBC Drivers section earlier in the article, after upgrading the Microsoft Data Access Components.
Jet Installable ISAM DriversIf your application uses Jet 2.x or earlier MDB files, dBase files, Excel spreadsheets, or any of the other installable ISAM file formats, then you need to install one or more of the following files to the Windows\System (Winnt\System32 for Windows NT or Windows 2000) directory:
The registry keys are given in the Microsoft Jet Registry Settings section at the end of the article. Verify the registry keys exist. If not, the section gives instructions on creating them through a .reg file.
Msrd2x35.dll Jet 2.x IISAM
Msexcl35.dll Excel IISAM
Msexch35.dll Exchange IISAM
Msltus35.dll Lotus 123 IISAM
Mspdox35.Dll Paradox IISAM
Mstext35.dll Text file IISAM
Msxbse35.dll dBase/FoxPro IISAM
You can also register them with the following commands:
Jet ProfilesIf you use custom Jet profiles, the following article provides more information:
ID articolo: 240377 - Ultima revisione: 27 ago 2008 - Revisione: 1