Unexpected Disappearance of Node Connections in n8n Workflows

Below is some background on what might be happening and steps you can take to investigate and resolve the issue.

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Possible Cause

In past releases there was a migration that removed empty output connections arrays. In some cases, due to the way workflows were stored and migrated, this could result in connections disappearing even if you didn’t make any manual changes.

This issue may also be related to workflow corruption in the database (especially when using SQLite) or to a migration running against your workflow data. Even if you haven’t updated workflows manually, the way that n8n processes and migrates its data can have unintended side effects.

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How to Fix

1. Check n8n Logs:
   Look in the container or application logs for any indications of migration or database errors. This might help pinpoint if an automated migration task removed connection data.

2. Inspect the Database:
   Use a tool like DBeaver to inspect your SQLite database. Look in the table where workflow JSON is stored (typically the workflow_entity table) to verify if the connections are missing from the stored workflow JSON.
   For example, you might run a query like:

   SQLCopied
   SELECT id, name, data 
   FROM workflow_entity
   WHERE name = 'your-workflow-name';

   Then check the JSON content for missing connections.

3. Restore from Backup:
   If you find that the connections are missing in the database, restoring from your latest backup may be the quickest way to recover the lost connections.

4. Update to a Fixed Version:
   If you suspect this behavior is due to a previously known migration bug, ensure you’re running a version of n8n that has that issue patched. Review the release notes for your version and consider updating if the issue has been addressed in a newer release.

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How to Monitor

• Enable Detailed Logging:
  Increase log verbosity (if possible) so that you can see detailed output from database migrations or workflow processing steps. This may help catch issues as they occur.

• Audit Workflow Executions:
  Use the Executions log within n8n to monitor if workflows later show discrepancies after execution. The log view might reveal if and when connections are being dropped.

• Periodic Database Checks:
  Schedule routine checks of the workflow data in your database to ensure the JSON representing node connections hasn’t been altered unexpectedly.

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By reviewing the logs and your database—and ensuring you’re on a version with the relevant bug fixes—you should be able to better understand and address the disappearing connections issue.