Source: https://docs.microsoft.com/en-us/office/troubleshoot/error-messages/this-file-cant-be-previewed
Symptoms
When you try to preview a document in the Preview pane, you receive an error message that resembles the following:
"This file can't be previewed because of an error in Microsoft Word previewer."
To work around this issue, preview the document in Windows Explorer or in a different Microsoft Office program. For example, preview a Microsoft Word document in Microsoft Excel or Microsoft PowerPoint.
For more information about this issue, consider the following scenario:
- You start one of the programs that are listed in the "Applies To Products" section.
- You click the Microsoft Office Button or the File tab, and then you then click Open.
- In the Open dialog box, you click Show the preview pane.
- You select a document to preview.
In this scenario, a preview of the document is not displayed. Additionally, you receive an error message in the Preview pane that resembles the following:
"This file can't be previewed because of an error in the Microsoft Word previewer."
This issue occurs because you must open another instance of the program to preview the document.