K2 blackpearl product versions and updates for product components are released simultaneously and with the same version number. When installing a particular version of K2, this means that all the components installed will have the same version number. When an update or upgrade is installed, all components that may already be installed must all be upgraded to the same version.
Whether K2 has been installed as a standalone system or in some form of a distributed configuration (including clustered and load balanced configurations on the same or adjacent domains with interaction between them), all the K2 components installed must be the same version. If any K2 component is a different version, unexpected system behavior may be encountered at design time or runtime.

For information on build numbers, versions and release dates, please refer to the KB article KB001421: K2 Product Releases and Build Numbers. That article also contains links to the release notes for each release.

An environment with a combination of different K2 product or component versions is not supported.

Verifying the K2 component version numbers

You can use the Windows Control Panel's Programs feature to retrieve a list of the installed K2 components and their versions.  For details on how to do this on various operating systems, please see the KB article KB001893: How to determine the installed K2 software version, updates and fix packs.

Determine the version number of K2 components installed on each machine, and then ensure that all the components have the same number (for example 4.16060.2000.1). In the case of distributed installs, you will need to check each machine where a K2 component is installed.

Correcting incorrect version numbers

To correct a system that uses a combination of versions, perform an installation or upgrade of the latest or required version for the components on the machines with the incorrect version numbers.

It is recommended to install the latest available version of a K2 product.

Considerations about K2 Assemblies/APIs

If K2 assemblies (for example SourceCode.HostClientAPI.dll, SourceCode.Workflow.Client.dll,  SourceCode.SmartObjects.Client.dll and others) have been manually distributed to machines or servers, those .dlls also need to be updated to the same version as the version on the target K2 server environments. Failure to do so may result in errors like "Invalid archive type".