XLIFF translations for the Machine Translation Service is disabled (SharePoint Server)
APPLIES TO: 
2013 2016 2019 Subscription Edition 
SharePoint in Microsoft 365
Rule Name: XLIFF translation for the Machine Translation Service is disabled.
Summary: There are several features in SharePoint Server that rely on the Machine Translation Service processing the XLIFF file format. If the .xlf extension is disabled, these features don't function correctly.
Cause: The .xlf file name extension is disabled for the Machine Translation Service.
Resolution: Enable the .xlf file name extension for the Machine Translation Service.
Verify that the user account that is performing this procedure is a member of the Farm Administrators group.
On the SharePoint Central Administration website, in the Application Management section, click Manage service applications.
On the Manage Service Applications page, in the list of service applications, click Machine Translation Service.
In the Enabled File Extensions section, select the check box for the .xlf file name extension under the XLIFF Parser.
Click OK.