Attempts to establish a new database connection in ArcGIS Pro fail and return the following error:
Error: Failed to connect to the specified DBMS instance. A database connection exception has occurred. A product licensing error occurred.
The keycodes file used to create the connection from ArcGIS Server is expired. The expiration date can be identified by opening the keycodes file using a text editor, for example, Notepad++, and checking the date specified in the strings provided in the file, as shown in the following image.
To resolve the issue, generate and retrieve the new keycodes file.