Invoice sync fault without reason

This article discusses scenarios in which an invoice synchronization fails, yet the sync logs do not provide any explanation for the failure.

Root Cause

In 2023, Xero implemented a Web Application Firewall (WAF) to inspect the data passing through the Xero API. If the firewall detects any "hacking terms" in the content, it will terminate the connection, causing invoices to fail syncing. Unfortunately, this disconnection does not provide any feedback, leading to an internal error in the sync process without triggering an alert email.

What types of phrases trigger the fault?

Words like cmd.exe, htaccess, 127.0.0.1 etc can all trigger the firewall to drop the connection.

What is the resolution?

Unfortunately, Xero cannot provide us with a comprehensive list of keywords that may trigger the firewall. Thus, we have taken the initiative to build our own internal dictionary as we come across these words.

If you encounter any issues with your invoices failing to sync properly, please inform our team, and we will promptly investigate the matter for you. In many instances, adding the problematic word to our internal dictionary can effectively resolve the syncing problem.