When does the error occur?
The error occurs when you are trying to associate your TestComplete test case with test cases, which are managed by Azure DevOps or Team Foundation server, via the Associate with Azure DevOps / TFS Test Cases wizard.
Why is the message shown?
The message is shown because TestComplete has failed to get information on the specified Azure DevOps test case. This can happen, for example, if the test case with the specified ID does not exist or if the connection to your Azure DevOps or Team Foundation Server has been lost.
Workarounds
Make sure your TestComplete project is connected to your Azure DevOps team project and can access it properly.
Make sure the specified Azure DevOps test case exists in your team project.