What is a UDB file? The UDB file format, which stands for “Dynamics AX User Database File,” is associated with Microsoft AX business management software, now known as Microsoft Dynamics 365 Finance and Operations. This file format is used to store important information related to user management and system components within the software. The UDB file typically includes a list of users who have access to the Dynamics AX system. It also contains information about the Component Object Model ...