Gmail shows a message like "No preview available" when it cannot display an attachment in its viewer. There are three common reasons.
1. Gmail cannot preview that file type
In received mail, Gmail's viewer handles common types such as PDF, JPG, TXT, HEIC, and Word, Excel and PowerPoint files. Many others (for example ZIP files, some design and data formats) have no preview. For those, download the file and open it with an app that supports it.
2. The message is in Spam
A user on Web Applications Stack Exchange found previews came back as soon as the message was moved out of Spam. Gmail limits what you can do with spam messages. If you trust the sender, open the message, click Report not spam, and try again.
3. The page or an extension is in the way
- Reload Gmail (Ctrl+R, or Cmd+R on a Mac).
- Try an Incognito window (Ctrl+Shift+N). If the preview works there, one of your extensions is blocking it; disable them in chrome://extensions and re-enable one at a time. For Acrobat, see Adobe Acrobat extension and Gmail PDFs.
See PDFs and images without leaving the thread
Attachment Preview is a free Chrome extension:
- PDFs and images (PNG, JPG, GIF, WebP) get a Preview button that opens them in a viewer on top of Gmail (overlay, page counter, Esc to close).
- Every other attachment gets Open in new tab. Types Chrome can display, such as text files, open in the tab. Types Chrome cannot display, such as ZIP or Word files, still download from that tab (for Word or Excel in received mail, click the attachment card to use Gmail's viewer).
It runs entirely in your browser and sends nothing anywhere. In compose, where Gmail downloads when you click a chip, Preview is how you check a PDF or image before sending without downloading.
Questions
Why do some attachments preview and others don't?
Gmail's viewer supports a set of common file types. Anything outside that set shows "No preview available" even when the file is fine.
Can I preview the file without downloading it?
For PDFs and images in received mail, yes, with Gmail's preview or Attachment Preview. For types no browser viewer supports, you need to download it and open it in an app.
Related: When Gmail won't preview a file · View Gmail attachments without downloading