Why Your WooCommerce Orders Aren’t Showing in Stamps.com – And How to Fix It

by | Jul 26, 2025

If you’re using WooCommerce with the Stamps.com Endicia plugin and suddenly your orders aren’t syncing, you’re not alone. This issue has become more common since WooCommerce introduced a new way of storing orders called High-Performance Order Storage (HPOS). While it’s great for speed and scalability, it can break compatibility with older plugins including shipping integrations like Stamps.com.

Here’s what’s going on and how to fix it in just a few steps.

Why aren’t your orders importing into Stamps.com?

The Stamps.com Endicia plugin expects to pull orders from WooCommerce using the legacy WordPress posts system and the legacy REST API.

If you recently:

  • Enabled High-Performance Order Storage (HPOS)
  • Or installed a new version of WooCommerce where HPOS is the default…

…then Stamps.com may no longer be able to “see” your orders.

Fixing the Stamps.com Endicia Plugin Woocommerce Import: Two Simple Settings

To get your WooCommerce orders flowing back into Stamps.com, follow these steps:

Enable Compatibility Mode for HPOS

This setting tells WooCommerce to synchronize order data between the new HPOS tables and the traditional WordPress posts table, which older plugins like Stamps.com rely on.

  1. Go to WooCommerce > Settings > Advanced > Features
  2. Scroll down to High-Performance Order Storage
  3. Enable “Synchronize orders between HPOS and WordPress posts storage” (also called “Compatibility mode”)
Image of Woocommerce settings and how to Enable Compatibility Mode

Also, Enable the Legacy REST API

Many older integrations including Stamps.com use WooCommerce’s original REST API. This was disabled by default in newer versions.

  1. Go to WooCommerce > Settings > Advanced > Legacy API
  2. Check “Enable the legacy REST API”
  3. Save changes

 

How To Enable Legacy Rest API in Woocommerce

After making those changes, it’s a good idea to:

  1. Deactivate and reactivate the Stamps.com plugin
  2. Clear any cache on your site or hosting
  3. Run a test order and attempt to sync again

Until Stamps.com updates their integration to support HPOS natively, this compatibility workaround is the safest and most effective way to keep your shipping workflow smooth.

Need help getting this set up? Feel free to reach out. We help businesses integrate and automate WooCommerce every day!