> For the complete documentation index, see [llms.txt](https://support.caspen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.caspen.com/integrations/quickbooks/fix-invoice-sync-errors-with-quickbooks.md).
# Fix invoice sync errors with QuickBooks
## Common QuickBooks invoice sync errors and fixes
### Create failed: Required param missing
**Cause:**
\
This occurs when an invoice has no line items.
**Fix:**
\
Revert to **Draft**, delete the empty invoice or edit it to add at least one line item (and tax if needed), then **Finalize**. Once you have finalized your invoice with line items it will automatically sync to xero. After you finalize, the invoice will sync to **QuickBooks** automatically.
***
### Update failed: Historical invoice
**Cause:**
\
This is shown on an invoice if it was created before connecting QuickBooks.
**Fix:**
\
Leave it as is, or recreate in Caspen if you need it in QuickBooks.
***
### Invalid refresh token
**Cause:**
\
An invoice fails because the connection to Quickbooks has expired.
**Fix:**
\
Disconnect and reconnect Settings → Integrations → QuickBooks, then click the Retry button.
***
### Duplicate document number
**Cause:**
\
This error occurs when you try to create an invoice where an invoice with the same number already exists in QuickBooks.
**Fix:**
\
Open that document in QuickBooks, change its number to something unique (add a prefix or extra digits), **save**, then return to Caspen and select **Retry**.
\
\&#xNAN;*For example:* *Use a unique scheme like* **INV{sequence}-{suffix}**, **CN{sequence}**, **ADJ{sequence}** *so they never clash with Caspen invoice numbers.*
***
### Business validation error (tax)
**Cause:**
\
This error occurs when a Caspen tax rate is not linked to a matching QuickBooks tax code (or that code does not exist or is inactive in QuickBooks).
**Fix:**
1. Note the tax on the invoice line items (e.g. GST, GST free).
2. Go to **Settings** → **Taxes**.
3. Find that tax rate and select **Actions** → **Sync with QuickBooks** → choose the matching **QuickBooks Tax Code** → Click **Sync**.
4. If the code is not in QuickBooks: create or enable it in QuickBooks, then repeat step 3.
5. If the rate is not in Caspen: add the tax rate in Caspen, then repeat step 3 to link it.
6. Return to the invoice → **Retry**.
{% hint style="info" %}
**Tip:** The QuickBooks tax code must exist and be active before Caspen can link to it.
{% endhint %}
***
### No QuickBooks status card showing
**Cause:**
\
The invoice was **voided in Caspen**. Caspen sends the void to **QuickBooks** and removes the **QuickBooks status** card from the invoice.
**Fix:**
\
No action needed. This is expected for voided invoices.
***
#### **Not seeing your error here?**
Please contact Caspen Support with: invoice number, a screenshot of the status area, the exact error text (if any), and the time you tried to sync. We will investigate and help you resolve it.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://support.caspen.com/integrations/quickbooks/fix-invoice-sync-errors-with-quickbooks.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.