Cancel Sales Order Error
Sales orders the connector could not cancel when the order was cancelled in Salla.
Open Cancel Sales Order Error
The link opens the screen directly in the Integration Dashboard.
The Cancel Sales Order Error screen
How the screen appears in the Integration Dashboard.

What this screen lists
Sales orders the connector could not cancel when the order was cancelled in Salla.
Common causes
The usual cause is that a document downstream of the sales order is still standing: Odoo refuses to cancel a sales order that has a posted invoice or a completed delivery.
The correct cancellation order is invoice first, then delivery, then the sales order. Make sure the status you use for cancellation appears in all three lists, not in the cancel-sales-order list alone.
How to clear it
Read the Odoo message on the row — it says exactly what is missing. Fix the cause in Odoo or in your settings, then press Retry on the row, or Retry Fix All if the cause is shared across every row.
Check the earlier screen first
If the same order appears on more than one error screen, start with the earliest in the pipeline. Fixing the first step usually clears the ones after it.