Users can not preview XLSX file type thorugh docViewerDescriptionXLSX files which are created directly from MS Excel, instead of being downloaded from the instance, can not be previewed by the docViewer, but only downloaded.Steps to Reproduce Activate the Document Viewer plugin. Attribute to "Use Document Viewer" is set to true for the table. Create a workbook on MS Excel. Save the workbook. Attach the workbook to the record on the table which the document viewer is configured for.Click on View to preview the document. Notice the error message: "This document could not be previewed".Optionally use Download Document.WorkaroundThis problem has been fixed in Paris. If you are able to upgrade, review the Fixed In section to determine the latest version with a permanent fix your instance can be upgraded to. The above behaviour is only observed when the attached XLSX file is a workbook from MS Excel. The workaround is to export the file from the instance as xlsx, which will allow preview.Related Problem: PRB1380517