Skip to main content
Open the source and read the message under its status badge — every failure shows a plain-language reason and the fix. Sync failed means the sync stopped early; Partial sync means it finished but some documents could not be synced. In both cases, everything that did sync is already searchable. The most common reasons:
  1. The source’s credentials were rejected. The account that set up the source lost access or its connection expired. Reconnect the source, then run Re-sync from the source’s menu.
  2. The system was temporarily under heavy load. Nothing is wrong with the source. Run the sync again; if it was a scheduled sync, it retries automatically on the next run.
  3. Some documents couldn’t be synced. The source page lists each affected document with the reason. Temporary issues retry automatically on the next sync; documents the provider refuses to share (unsupported formats, revoked access) stay skipped until that changes.
  4. Group membership could not be read (sources with Document access set to Original source). Files shared through groups may be hidden from search until an organization admin checks the organization’s directory connection, or the source is reconnected with an account that can view users and groups.
  5. The source was paused mid-sync. Not an error — resume the source and sync again.
Whoever ran the sync also gets a failure email with the same reason, so you do not have to watch the page.

​
FAQ

Sync failed means the run stopped before finishing. Partial sync means the run completed, but specific documents were skipped — open the source to see which ones and why.
Documents skipped for temporary reasons are retried on the next sync automatically. Documents skipped because the provider would not hand them over stay skipped until the underlying cause is fixed.
No. A failed sync never removes what was already indexed — search keeps working with the content from the last successful sync.
Reconnect the source’s credentials and check its settings. If it still fails, contact support.

How often does Brain sync?

Automatic and manual syncs

Why is a document missing?

Permission-based reasons