How to restrict the files that users can upload in the form?

File upload question allows images, documents, audios, videos, html files by default. You can accept only specific file types by adding the list of extensions for the acceptable file types for the file upload question in the Formfacade customize interface.

Step 1: Open your Google Forms > click on the addon icon > select Formfacade > Select Customize this form > Click on the Proceed button.
Step 2: In the Formfacade customize interface, click on the gear icon next to the file upload question.
Step 3: Field settings screen will be displayed. Select the answer tab. By default, file upload accepts the following file types: pdf, doc, docx, xls, xlsx, csv, txt, rtf, html, zip, mp3, wma, mpg, flv, avi, 3gp, m4v, mov, mp4, wmv, jpg, jpeg, png, gif
Step 4: To restrict the file types that users can upload, add the extensions of the acceptable file types separated by commas as shown below. For example, you can add the extensions pdf, doc, docx to accept only these three file types.
When the user clicks on browse files, only the accepted file types can be selected. Users will be able to upload files with accepted extensions that does not exceed the max file size limit.