Troubleshooting issues with suggested media and link details

When you paste a link into the Buffer composer, we’ll scan the page and suggest images and metadata (like title and description) for your post. If your link preview isn't looking quite right, this guide explains how Buffer pulls in that information, how you can optimize your site, and how to troubleshoot any issues.

How Buffer finds images from URLs

When you add a link to the Buffer composer, Buffer uses our dedicated scraping bot to scan the page for images and then suggests them to use with your post. You can find all the information about our link preview bot here: About Our Bot.

Here’s how it works:

• The scraper checks for Open Graph tags (like og:image    ) in the HTML.
• It then scans the first 24 images, in groups of 8, until it finds at least 5 that meet certain requirements.
• Only the first 15 valid images will be considered for Suggested Media.
• Buffer checks that each image has a width or height attribute and that the image is large enough (at least 200x200 pixels) and reasonably square.
• Only JPG, PNG, WEBP, and BMP images can be used as Suggested Media. GIF and SVG images will not appear as options, even if they otherwise meet the size and format requirements.

Once Buffer finds a usable image, it copies that image into Buffer's own storage rather than linking directly to the image on the original site. This means suggested images and link preview thumbnails must pass the same file type, size, and channel limit checks as any image you upload yourself. If an image can't be copied for one of these reasons, Buffer will tell you why, and the suggested image won't attach to your post. For link preview thumbnails, the original image will be used instead.

If the first 8 images are valid, Buffer stops there and uses those as the Suggested Media. This keeps things efficient and fast.

:::tip Tip: A properly formatted image might look like this:

<img src="link-to-your-image" width="600"/> :::

What metadata does Buffer use to generate link previews?

• Open Graph images first: The scraper checks for Open Graph tags (like og:image, og:image:secure_url, og:image:url) and Twitter Card images (twitter:image, twitter:image:src) in the HTML.
• Article images: It prioritizes images within <article> tags or elements with itemprop="articleBody".
• General page images: It then scans other images on the page.
• Batch processing: The scraper processes up to 24 images total in batches of 15, until it finds at least 5 that meet the quality requirements.

We recommend following the Open Graph Protocol when setting up your website so that Buffer (and other platforms) can pull the correct information.

How to validate your link

To check what metadata is available for your link, we suggest using the Facebook Sharing Debugger or Buffer's scraper debugging tool.

Paste your URL there to:

• See which metadata is available
• Confirm which images are being pulled
• Refresh Facebook's (and Buffer’s) cached version of your link

:::info Note: These guidelines are for those who are sharing links to pages that they own and have control over. If you are sharing links to websites that you do not own, it is not possible to control which images are pulled in. :::

Common errors with sharing links and how to fix them

In some instances, Buffer's scraper can be prevented from accessing the information for the site to generate a link attachment. This can be due to the site's security configurations or the robots.txt. In both instances, Buffer will need to be explicitly allowed. You can find the information needed to create the rule, exception, or allowance here.

If you see the error, FetchError: request to [your URL here] failed, reason: unable to verify the first certificate - _UNABLE_TO_VERIFY_LEAF_SIGNATURE,_   your website admin might need to update the SSL certificates as the website server is not correctly presenting the full SSL certificate chain. To resolve this, ask the website owner or admin to try to get the SSL certificate up to date.

If a suggested image or link preview thumbnail fails to attach, Buffer will show a message explaining why the image couldn't be copied into your Buffer account. This usually means the image doesn't meet the file type, size, or channel limit requirements for the channel you're posting to. Check the image against the supported formats and size limits for your channel, and try a different image if needed.

Best practices for optimizing your site for Buffer

Here are a few tips to ensure Buffer can pull the correct content from your links:

• Add proper Open Graph tags to your HTML (og:title    , og:description    , og:image    )
• Place your og:image    tag near the top of your page’s HTML
• Use a supported image format (JPG, PNG, WEBP, or BMP) at the recommended size. GIF and SVG images won't show up as suggested media.
• Avoid blocking bots like Buffer’s in your firewall or server settings
• Test and refresh your link using the Facebook Sharing Debugger

Still need help?

If you've tried the suggestions above and things still aren’t working as expected, feel free to reach out to us at hello@buffer.com — we're always happy to help!