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Slack Link Preview Not Working? 6 Fixes to Try

You paste a link in Slack and nothing happens — just a plain URL. Here are the 6 most common causes and how to fix each one.

Slack link preview not working?

Check your Open Graph tags free with Proovd — paste a URL and see exactly how it looks on Slack, X, LinkedIn, Discord, WhatsApp, and Reddit.

Quick Answer

  • Slack needs valid og:title, og:description, and og:image tags
  • Check workspace settings — link unfurling may be disabled
  • Slack caches previews — delete the message and re-post

Why Slack Ignores Your Link

Slack link previews (called "unfurls") are powered by Open Graph tags, but Slack adds an extra layer of complexity: workspace-level settings that control whether links unfurl at all.

Fix 1: Enable Link Unfurling in Workspace Settings

This is the #1 cause of missing Slack previews. If unfurling is disabled, no links will show previews — regardless of your OG tags.

  1. Go to Workspace Settings (click your workspace name → Settings)
  2. Go to Message Prefill
  3. Make sure "Unfurl links in messages" is enabled
  4. Save changes

Individual channels can also override this setting. Check the channel settings if only specific channels don't show previews.

Fix 2: Check Your OG Tags

Slack needs these Open Graph tags to render a preview:

<meta property="og:title" content="Your Title" />
<meta property="og:description" content="Your description" />
<meta property="og:image" content="https://yoursite.com/image.jpg" />
<meta property="og:url" content="https://yoursite.com/page" />

Slack is relatively lenient about image size (it will display almost any image), but missing og:title or og:image will result in no preview at all.

Use Proovd to verify your tags are complete.

Fix 3: Check for robots.txt Blocking

Slack's crawler must be able to fetch your page. If your robots.txt blocks Slack's bot, no preview will appear.

Slack's crawler user agent is Slackbot-LinkExpanding 1.0. Make sure your robots.txt doesn't block it:

User-agent: Slackbot-LinkExpanding
Allow: /

Fix 4: Clear Slack's Cache

Slack caches link previews. To force a refresh:

  1. Delete the old message with the broken preview
  2. Re-post the same URL
  3. Slack will re-fetch and render the updated preview

Fix 5: Check If Your Page Returns an Error

If your page returns a 4xx or 5xx error when Slack's crawler fetches it, no preview will appear. This is common with:

Fix 6: Check Image Accessibility

Slack needs to fetch your og:image URL directly. If the image is behind authentication, blocked by CORS, or returns a 403/429 error, Slack can't use it.

Quick Fix Checklist

  1. Enable link unfurling in workspace settings
  2. Confirm og:title, og:description, and og:image tags are present
  3. Ensure image URL is absolute and publicly accessible
  4. Check robots.txt allows Slackbot-LinkExpanding
  5. Delete old message and re-post URL
  6. Verify with Proovd before posting

Frequently Asked Questions

Does Slack use Twitter Card tags?

Slack primarily uses Open Graph tags. It may fall back to Twitter Card tags if OG tags are missing, but you should always set OG tags first.

Why do some Slack channels show previews and others don't?

Channels can have their own unfurling settings that override workspace-level settings. Check the channel settings for each one.

Related Articles

Check your Slack link preview before you share

Check your Open Graph tags free with Proovd — paste a URL and see the preview on X, LinkedIn, Slack, Discord, WhatsApp, and Reddit.