Failed to connect to database. An underlying database error occurred. Could not start session

Error Message

Note:
This article pertains to ArcGIS versions 9.x. Later versions of ArcGIS may contain different functionality, as well as different names and locations for menus, commands and geoprocessing tools.

When trying to access many personal geodatabases (pGDB) (e.g., more than 126 unique pGDBs) in ArcMap or ArcCatalog, the following error message is displayed:

"Failed to connect to database.
An underlying database error occurred. Could not start session."

Solution or Workaround

Convert the data to file geodatabases.