QuickBooks Online

QBO Error - "TxnID Cannot Be Linked"

Explanation: Two entities or transactions can be linked only if they belong to the same Customer or Job.

If you see this error, it means that the transactions you are trying to link (invoice and payment, for example) are referring to different customers.

How to Fix:

Recreate the payment under the same customer as the invoice you are trying to pay. Then, delete the original payment.