Accessing UT feature classes with an external program, such as ArcCatalog, ArcMap, ArcReader, FME, Python, MxdPerfStat (UT layers are not displayed here), etc., does not succeed.
This behavior occurs when there is no UT installed on the computer where you run the program. It is caused by the feature class extensions of UT.
Feature class extensions contain special programme code for UT. They are called each time the feature class is addressed.
These extensions are managed by ArcGIS. For this purpose, they are registered with ArcGIS and a reference to them is placed in the Windows Registry.
The UT feature class extensions can be found in the installation component called UT Components. The UT Components provide the UT base components.
It is sufficient to install only the UT Components.
When installing the UT Components, the UT feature class extensions are registered for all installed ArcGIS products (ArcGIS Desktop/Engine and/or ArcGIS Server).
The UT Components are part of the installer for UT DesktopSuite and UT ServerSuite. If you want to install only UT Components, you have to uncheck everything except UT Components when selecting components.