3rd Party: Customer.io connector failing with '500 Internal Server Error' for customer endpoint.

Incident Report for Fivetran

Resolved

The incident has been resolved. We are observing instance rates returning to normal, and affected connections are now syncing successfully.

Incident Summary
Description:
We identified an issue affecting the customer.io connections, which caused syncs to fail with a '500 Internal Server Error'.

Timeline:
This issue started on January 21 at 9:23 AM UTC and was resolved on January 21 at approximately 2:53 PM UTC.

Cause:
The incident was caused by an issue on the third-party provider’s side.

Resolution:
To restore syncing, we temporarily skipped the Customer table to allow the connector to sync. Once a fix is confirmed by the customer.io team, syncing will resume from the point where the connector last stopped for this table.
Posted Jan 21, 2026 - 16:28 UTC

Monitoring

We have applied a fix that temporarily skips the Customer endpoint to allow syncs to complete successfully. We will continue to monitor all affected connectors until they return to normal sync behaviour.
Posted Jan 21, 2026 - 14:26 UTC

Update

We are continuing to work on a fix for this issue.
Posted Jan 21, 2026 - 10:36 UTC

Identified

We have identified an issue with the Customer.io connector where syncs for the customer endpoint are currently failing. As a temporary measure, we are skipping this table while we work with the Customer.io team to resolve the issue.
Posted Jan 21, 2026 - 09:50 UTC
This incident affected: Systems (General Services).