This occurs after upgrading Internet Explorer to version 11.
The K2 Workspace no longer functions correctly and an error "This operation requires IIS integrated pipeline mode" appears.
When the pipeline mode is changed to integrated mode, a "500" error appears.
The issue is caused by the K2 URLs not being added on the trusted sites list, as well as the compatibility view site settings.
The K2 URLs are the workspace runtime URLs, as well as all the other base URLs used.
Complete the following workaround:
Please ensure the document mode is set to "Edge" and add your K2 URL to the Compatibility view setting on the browser e.g "denallix.com."
Then go to Internet Options and add the same site to the Trusted sites.
From the Trusted sites option, click on "sites" and add all your site URLs.
For example: "*.denallix.com"
Another workaround would be to use the option: "Set enterprise mode to True".