User get error massage "Unable to Open File" when trying to open document via Box Edit.
Please check the following if you are receiving the "Box Edit failed to validate the file download" error:
1. Check that you are using a supported browser. Unsupported browser may not work with Box Edit.
2. Check if you are using a browser mode that does not allow cookies. For example, Chrome's Incognito mode or Internet Explorer's InPrivate Browsing mode.
3. Check if your browser settings are configured to not allow cookies. Cookies need to be allowed or an exception for Box should be added. Cookie settings vary depending on the browser: