WorldServer - Legacy Filter configuration cannot be imported in version 11.7.x and 11.8.x - Error parsing deployment XML: class com.idiominc.ws.filters.htmlnt.config.HTMLNTConfigData cannot be cast to class com.idiominc.ws.filters.fts.FSProxyFilterConfigu

As you know, we still "support" Idiom filters meaning that they are available in WorldServer and can be applied to segment source files.
Also, Idiom filter configurations can be edited in the User Interface (while File Types need to be edited in Trados Studio)

However, if you export such an Idiom filter configuration from Management > Administration > Export Objects and then import the object (*.TML file) into a different WorldServer environment, the import will always fail with an error. Note the error varies slightly depending on which filter configuration is being imported. In the example below, this is an error related to an HTML (NT) filter configuration, hence the reference to HTMLNTConfigData. However, the same error appears when trying to import any other Idiom filter configuration.
 
 Error parsing deployment XML: class com.idiominc.ws.filters.htmlnt.config.HTMLNTConfigData cannot be cast to class com.idiominc.ws.filters.fts.FSProxyFilterConfigurationData (com.idiominc.ws.filters.htmlnt.config.HTMLNTConfigData and com.idiominc.ws.filters.fts.FSProxyFilterConfigurationData are in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @48cb4ed6)

Import failed

The issue has been filed as defect CRQ-31948. 

Workaround:

1- Open the TML file in Notepad++
2- Identify the elements filterConfig id and <configName>. You will notice that the configuration name after | and the one included in the <configName> are identical. This is what causes the problem. Here is an example:

<filterConfig id="HTML (NT) Filter|Haiku_HTML" exported="true">

  <configName>Haiku_HTML</configName>

3- To fix the issue, in the configName tag, simply modify the name so that it's no longer identical to the name in the filterConfig id attribute.

For example, change as follows:

<filterConfig id="HTML (NT) Filter|Haiku_HTML" exported="true">

  <configName>Haiku_HTML1</configName>

4- Save your change.

With this change, the Legacy filter configuration (TML file) will be imported without error.