This guide is for Gmail in Chrome on a computer or Chromebook. (On a phone, update the Gmail app and the app that opens the file type.)
Find your symptom
| What happens | Go to |
|---|---|
| Nothing happens when you click | Steps 1 and 2 |
| Preview shows an error | This fix |
| "No preview available" | This fix |
| The file downloads instead of opening | This fix |
| PDFs open in a new tab or in Adobe | This fix |
| You are in compose and every chip downloads | Preview before sending |
1. Reload Gmail and update Chrome
Reload with Ctrl+R (Cmd+R on a Mac). Then open chrome://settings/help; Chrome checks for updates and asks you to relaunch if one is ready.
2. Test without extensions
Open an Incognito window (Ctrl+Shift+N) and sign in to Gmail. If attachments open there, an extension is interfering. Turn extensions off in chrome://extensions and back on one at a time. For Acrobat specifically, see Adobe Acrobat extension and Gmail PDFs.
3. Check Chrome's PDF setting
At chrome://settings/content/pdfDocuments choose Open PDFs in Chrome.
4. Clear Gmail's site data (last resort)
At chrome://settings/content/all search for mail.google.com and clear its data. You will be signed out of Gmail and need to sign in again.
5. Check the file
Files over 25 MB arrive as Google Drive links. If the same file fails everywhere, ask the sender to resend it.
A one-click alternative for PDFs and images
Attachment Preview is a free Chrome extension that adds a Preview button under PDF and image attachments in Gmail. The file opens in a viewer on top of your inbox (overlay, page counter, Esc to close). Other files get Open in new tab, which shows types Chrome can display (Word or Excel files still download from that tab; use Gmail's viewer for those in received mail). It works in opened emails and in compose, and nothing leaves your browser.
Related: Gmail PDF preview not working · On a Chromebook