If you have installed a 64-bit version of QGIS on Windows and you find that GeoDatabases Personal (* .mdb) does not work anymore, this solution can solve the problem.
If you did not install Microsoft Office 64-bit on your machine, install microsoft access database engine 64 bit.
This method solves the problem for QGis versions 2.18 and 3.0.
In the Environment Variables panel of Windows Advanced System Settings, set the following two new variables as user variables or system variables:
name of the variable: OGR_SKIP
value: ODBC
name of the variable: PGEO_DRIVER_TEMPLATE
value: DRIVER = Microsoft Access Driver (* .mdb, * .accdb); DBQ =% s
To load a feature class from the geodatabase you will follow the following steps:
For QGis 2.18
Go in Layer-> Add Layer -> Add Vector Layer
Leave the File option selected, and click Browse
Point to the personal geodatabase.
Click Open. A window opens that allows you to choose one or various feature classes contained in the geodatabase to load.
For QGis 3.0
Go in Layer-> Add Layer -> Add Vector Layer
Leave the File option selected, and click on the button … section Source.
Point to the personal geodatabase.
Click on the button Add. A window opens that allows you to choose one or various Feature classes contained in the geodatabase to load.