Starting from FlexiCapture 12 Release 3 Update 2 (build 12.0.3.4038) onwards, the behavior when assigning an empty string to IPage.ResultClassName property has changed.

Previously, the application allowed this operation. Starting from build 12.0.3.4038 this now will lead to an exception with the following message:

System.Runtime.InteropServices.COMException (0x80004005): The result class name does not match any class in the classifier.

Workaround

The script should be modified to avoid assigning empty strings.
As example, by adding a condition around the operation to make sure that the assigned string is not empty.

Code sample (C#):

  if ( ! string.IsNullOrEmpty(result.ClassName) )
  {
    Page.ResultClassName = result.ClassName;

    // ... other code, as needed
  }

  // if the condition is not satisfied, no assignment is performed