Bluesky

What to Review When a Scheduled Bluesky Post Fails

When a scheduled Bluesky post fails, the cause is usually found in three areas: App Password health, strict 1MB media blob limits, or PDS connectivity. Learn how to diagnose and fix AT Protocol publishing errors.

Paul Onu

Aug 8, 2026 — 4 min read

When a scheduled Bluesky post fails to publish, the root cause is rarely a mystery of the algorithm. Because Bluesky is built on the AT Protocol (Authenticated Transfer Protocol), failures are almost always tied to specific technical constraints: credential expiration, media blob size limits, or Personal Data Server (PDS) connectivity. Unlike legacy social networks, Bluesky’s decentralized nature means your post isn't just hitting a central database; it is being written as a record to your specific repository.

To resolve a failed post, you must move through a diagnostic hierarchy that starts with authentication and ends with network-specific rate limits. Use this guide to identify why your content stayed in the queue and how to ensure the next one goes live.

1. Validate the App Password and Token Health

Bluesky does not typically use standard OAuth in the same way as older platforms for third-party scheduling. Instead, it relies on App Passwords. If your scheduled post fails, the first point of failure is often the validity of this specific credential.

Check for Revocation: If you recently changed your main Bluesky password or cleaned up your settings, the App Password used by your scheduling tool may have been revoked.
Scope Permissions: Ensure the App Password was created with the necessary permissions to write to your repository. A "read-only" password will allow a tool to show you analytics but will fail the moment a publish command is sent.
Session Expiration: While App Passwords are long-lived, the session tokens derived from them can expire if the scheduling service has not refreshed them within the protocol's required window.

If you suspect a credential issue, the fastest fix is to generate a fresh App Password in your Bluesky settings (Settings > App Passwords) and reconnect it to your publishing workspace.

2. Inspect Media Blob Constraints

Media handling is the most common technical hurdle for Bluesky users. While the Bluesky mobile app might feel seamless, the API (specifically the com.atproto.repo.uploadBlob lexicon) enforces strict limits that differ from platforms like Instagram or X.

The 1MB Limit

As of current protocol standards, individual image blobs uploaded via the API are generally capped at 1,000,000 bytes (approximately 1MB). If your scheduling tool does not automatically compress or resize images, a high-resolution JPEG from a professional camera will trigger an immediate BlobTooLarge error.

The Four-Image Rule

Bluesky currently supports a maximum of four images per post. If your workflow involves cross-posting content from a platform that allows more—such as an Instagram carousel—the post will fail if the fifth image isn't manually removed or handled by your scheduler's channel-specific variant settings.

Alt Text Requirements

While not always a hard failure for the protocol itself, many professional publishing workflows and some third-party API implementations treat missing alt text as a validation error. Bluesky’s culture and technical architecture prioritize accessibility; ensure your pre-publish quality checklist includes a step for descriptive image text.

3. Review PDS and Relay Connectivity

Because Bluesky is federated, your account lives on a Personal Data Server (PDS). For most users, this is bsky.social, but for those using custom domains or independent hosting, the PDS might be different.

PDS Downtime: If the server hosting your data is down, the post cannot be written to your repository. You can check the status of the main Bluesky PDS at status.bsky.app.
Relay Lag: Sometimes the post is successfully written to your PDS, but the "Relay" (the service that crawls the network to show posts in the global feed) is lagging. In this case, the post exists on your profile but doesn't appear in feeds. This isn't a scheduling failure, but a network synchronization delay.

4. Diagnostic Table: Common Bluesky Error Codes

Error Code / Symptom	Likely Cause	Required Action
`Authentication Failed`	App Password revoked or expired.	Generate new App Password in Bluesky settings.
`BlobTooLarge`	Image exceeds 1MB limit.	Resize or compress image below 1,000,000 bytes.
`RateLimitExceeded`	Too many posts or actions in a short window.	Wait 60 minutes; reduce frequency of automated posts.
`InvalidRequest`	Malformed post structure (e.g., > 300 characters).	Check character count; Bluesky limit is 300.

5. Establishing a Fail-Safe Workflow

To minimize failures, your publishing process should account for the specific quirks of the AT Protocol. Rather than treating Bluesky as an afterthought to your X or Instagram strategy, adapt your content specifically for its constraints.

Use Channel-Specific Variants

Avoid sending the exact same payload to every network. A post that works on LinkedIn might be too long for Bluesky’s 300-character limit. Use a tool like Postly to create a Bluesky-specific variant of your post. This allows you to trim the text and ensure images are optimized for the 1MB blob limit without affecting your high-resolution posts on other platforms.

Pre-Validation Checklist

Before hitting 'Schedule,' verify the following:

Character Count: Is it under 300 characters? (Note: Links count toward this total).
Image Count: Are there 4 or fewer images?
File Size: Is each image compressed for web delivery?
Link Facets: If you are using the API directly, ensure your "facets" (the byte-offsets for links and mentions) are calculated correctly. Most modern schedulers handle this automatically, but manual errors here will cause the post to display as plain text rather than clickable links.

Summary of Next Steps

If a post has already failed, do not simply try to re-send it repeatedly, as this can trigger rate limits. Instead:

Check the error log in your scheduling dashboard for specific AT Protocol strings.
Verify your PDS status.
Manually upload one image to the Bluesky web interface to confirm your account isn't restricted.
Adjust your campaign brief to include a "Bluesky-optimized" asset tier with smaller file sizes.

By understanding that Bluesky is a protocol-first network, you can move from reactive troubleshooting to a proactive workflow that respects the technical boundaries of the decentralized web.