From late September until October 5, 2026, some Substack posts scheduled through Buffer became stuck in processing and did not publish. The issue mainly affected video posts, with around 200 posts across 60 customer accounts affected.

Our publishing service ran out of memory while uploading videos. A separate problem prevented email and push notifications for these failed posts from reaching customers. Our monitoring also missed the failures, which delayed our response.

On October 5, we increased the service’s memory capacity and confirmed that video posts were publishing successfully again. Previously failed posts were not published automatically. If you still have affected posts, you can select Retry Now on each one when you’re ready to publish it.

We also found that the job responsible for handling stuck posts was running an outdated version that lacked Substack support. We corrected its deployment process and added safeguards to prevent services from silently missing updates.

Our remaining work includes verifying failure notifications, improving monitoring to catch stuck posts on individual networks, and reviewing how many videos the service processes at once.

We’re sorry these posts did not publish, and that we failed to notify you promptly.