WhatsApp has made it even easier for its 1 billion active users to communicate, adding the option to share documents in a chat. This feature is rolling out today (Mar. 2) as a server-side update to users who have the most recent version of the app, so you may need to nudge your friends to update.
While document sharing is landing on both iOS and Android versions of WhatsApp, it works slightly different on each platform. On Android, you first tap the Paperclip icon and then select the Document icon, while iOS users need to tap on the upload arrow to find the Share Document option.
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Android users will be shown a list of the documents available for sharing on their device, but iOS users will first need to select a source (including iCloud Drive, Dropbox and Google Drive) and then hunt for the file they want to share. At this time, WhatsApp's document sharing only supports PDFs, but it may just be a matter of time before WhatsApp bakes in support for other kinds of files.
While you're sending the file to your friend, you both see a preview of the document with its total page count and file size. After Android users share a document, it will appear in the Media/WhatsApp Documents folder, and the file's contents will be searchable in WhatsApp.
For more about the chat app, check out the Tom's Guide How to Use WhatsApp tutorial, a guide for everything from setting your account up to mastering the service's hidden features.
And in case of Group messages, if any of the person from the Groups members list don't have the updated version of Whats app then still you can't send the document file.
In short everyone should have the updated version to send and receive the documents like PDF