Unable to open a personal geodatabase (.mdb) or create a new one

Last Published: April 25, 2020


In ArcCatalog or ArcMap personal geodatabases are not visible, data contained in the .mdb cannot be accessed, and a new personal geodatabase cannot be created.


Libraries for Microsoft Access may not be properly registered. To test and determine if this is the cause, open Microsoft Access and attempt to create a new Access database (.mdb). If a new Access database cannot be created refer to the solution below.

Solution or Workaround

Click Start > Run and register the following files:

• dao360.dll
• msacc.olb

The paths to these files depends on the computer operating system and the version of Microsoft Office installed on the computer.

A sample of the command syntax to enter in the Windows Run dialog box is as follows:

regsvr32 "C:\Program Files\Common Files\Microsoft Shared\dao\dao360.dll"

The full path to the library location must be placed in double quotes because there are spaces in the path name.

Here are samples of the possible locations for these files:

• C:\Program Files\Common Files\Microsoft Shared\dao\dao360.dll
• C:\Program Files\Microsoft Office\OfficeXX\msacc.olb
• C:\Program Files (x86)\Common Files\Microsoft Shared\dao\dao360.dll
• C:\Program Files (x86)\Microsoft Office\OfficeXX\msacc.olb

This problem may also be related to the problem of being unable to access styles, create new styles, or add symbols to an existing style, as described in Knowledge Base article 39797.

If attempting to register either of the above files returns an error or fails:

• Perform a clean uninstall and reinstallation of ArcGIS for Desktop.
• Uninstall any custom styles or third-party extensions and styles.
• The user profile may be corrupt. Check the installation by logging in to another account on the system or network. If necessary, repair the corrupt user profile.
• Review the installation or administrative rights of Microsoft Access on the system.

If further assistance is needed, contact Esri Support Services at 888-377-4575 or at

Article ID:000011462

  • ArcMap

Get help from ArcGIS experts

Contact technical support

Download the Esri Support App

Go to download options

Related Information

Discover more on this topic