Previously, the model history databasedatabase file that collects model history on the actions in the model
was permanently upgraded when opening a Tekla Structures 21.0 version model in a newer version of Tekla Structures. This caused problems if the model was closed without saving, as the history database remained upgraded, renderingprocess of making the model object faces visible
The rendered model object faces can be transparent or non-transparent
it incompatible with version 21.0.
Now the upgraded history database is restored to the original version when the model is closed without saving.