On March 6, 2019, Autodesk released this Hotfix for Revit. After this Revit hotfix is applied successfully, the build number specified on the help about will be 188.8.131.52.
Issues resolved by Revit 2019.2.1 Hotfix
This hotfix includes new functionality, addresses issues and crashes reported directly to Autodesk, and contains the fixes included in previous Revit 2019 updates and fixes. Consult the release notes for all areas improved by this hotfix.
Additional software applied by this hotfix
With this install, the following will be updated: Revit 2019, Collaboration for Revit 2019, Dynamo Core, and Dynamo Revit.
Known issues after applying this hotfix
If Revit 2019 and Revit LT 2019 are installed side-by-side and the 2019.2.1 Hotfix is only applied to one of these products, a “Could not load type ‘Autodesk.Revit.DB.ICloudExternalServer’ from assembly” error will be displayed when launching the non-updated product. To alleviate this error, make sure to apply the 2019.2.1 Hotfix to both Revit and Revit LT in side-by-side configurations.
For more info refer to the online readme file
•Who should install this hotfix?
•Supported operating systems
•General installation information
•Installation instructions •Apply this hotfix to an existing installation
•Apply this hotfix to a deployment installation image
•Uninstall this hotfix