Warning:[…]/wp-content/plugins/jetpack/class.photon.php on line 91

I too encountered the same after updating WordPress SEO. For me the error message is appearing only on posts with gallery images.

The first thing to check is whether any other plugins on your site may have a conflict. Please check our Known Issues list here:
https://jetpack.me/support/getting-started-with-jetpack/known-issues/

You can also try to deactivate all plugins on your site, and see if that resolves the issue. If it does, then activate them one at a time to determine which is causing the conflict.

If that doesn’t help, please rule out a theme conflict by temporarily changing your site’s theme to a default theme (such as Twenty Fifteen) and trying again.

Please let me know how that works for you!

When I disabled Yoast WordPress SEO the issue got resolved. But being a frequent publisher I can’t work without Yoast.

I had the same problem:
“Warning: preg_match_all() expects parameter 2 to be string, array given in /home/content/72/9209272/html/blog/wp-content/plugins/jetpack/class.photon.php on line 91” at the top of the page.

QUICK FIX
Go to Jetpack settings and disable Photon until Yoast fixes the problem with a new update release. The warning goes away.

Have reported the issue with Yoast. They might come-up with a fix soon.

We’ve received a few more reports of this issue, and it does indeed appear to be a conflict with the WordPress SEO plugin. This conflict has been reported to their team, and they appear to be working on it at the moment. You can follow along with their progress here:
https://github.com/Yoast/wordpress-seo/issues/2001

I’ll update this thread when the issue has been resolved. Please let me know if you have any questions that I can help with in the meantime!

Looks like I’m not the only one with this issue. Thanks for the quick fix Richard!

We released a small Jetpack update today that includes a fix for this issue. You should receive an update notification in your dashboard soon, if you haven’t updated already.

Alternatively, you can download the latest version of Jetpack and manually update it yourself:
https://www.ads-software.com/plugins/jetpack/changelog/

If anyone has any questions, or runs into any further trouble, please don’t hesitate to let us know!

Thanks Ryan!

Thanks.

You’re welcome! I’m going to mark this thread resolved, but please let me know if you have any other questions.