Topic

If you still have custom application running on 32-bit, and you want to use the custom application to interact with K2, you will need to add the 32-bit version of SourceCode.HostClientAPI.dll and SourceCode.Workflow.Client.dll as your application's dependencies.

However, the SourceCode.HostClientAPI.dll and SourceCode.Workflow.Client.dll found in [Program Files]\K2\Host Server\Bin and [Program Files]\K2\Bin have been changed to 64-bit in recent K2 Five or Nintex Automation On-Prem versions.

Instructions 

The 32-bit assemblies can be found in the following locations:

C:\Windows\assembly\GAC_32\SourceCode.HostClientAPI\4.0.0.0__16a2c5aaaa1b130d\

C:\Windows\assembly\GAC_32\SourceCode.Workflow.Client\4.0.0.0__16a2c5aaaa1b130d\

Additional Information

We highly recommend you update your custom application to 64-bit if possible as there is no guarantee the 32-bit assemblies will still be installed in future versions.