EZ Preorder Help Center Install on Shopify

The preorder button does not update when switching variants

All plansLast verified 11 November 2026View as Markdown

EZ Preorder & Back In Stock decides for each variant whether to show the preorder button, so it has to notice when a shopper picks a different variant. By default it watches your theme's variant input, which some themes change without announcing it. When that happens the button stays as it was until the page is reloaded. Fix it by choosing your theme preset, then by turning on Variant switch override, and contact support if neither works.

Available on: All plans.
Where to find it: EZ Preorder → Configuration → Theme Settings.

How EZ Preorder follows variant changes

When a product page loads, EZ Preorder reads the selected variant from the element matched by Variant selector (default [name="id"]). After that, it follows changes in one of two ways:

  • No custom script saved (Variant switch override off). EZ Preorder listens for the variant input's change event. Themes that update the input silently, or replace it with a new one, are missed.
  • A custom script saved (Variant switch override on). EZ Preorder runs the script instead, and the script reports each new variant. The generic script follows the variant number in the page address (?variant= in the URL).

Each time EZ Preorder sees a new variant, it shows the preorder button if that variant is on your preorder list, enabled and meets its rule, and otherwise brings back your theme's own add to cart button. If your theme redraws the product form after a variant change and removes the preorder button, EZ Preorder adds it back.

Check that it is a variant switching problem

  1. Go to Preorders in EZ Preorder, expand the product, and note each variant's rule badge and stock. With the Sold out rule, for example, an in-stock variant correctly shows your normal add to cart button.
  2. On your live store, pick the variant that looks wrong, then reload the page.
  3. If the button is right after reloading but wrong after switching, the problem is variant switching: choose your theme preset, then try Variant switch override, then contact support. If it is wrong even after reloading, see The preorder button is not showing on my product page.

How to fix the preorder button on variant switch

  1. Choose your theme preset. Go to Configuration → Theme Settings. In the Theme Selector card, click Select Theme (or Change preset), search for your theme, tick it, click Select, then click Save. Many presets include a variant script made for that theme. Test again.
  2. Turn on Variant switch override. If your theme has no preset or the problem remains, turn on Variant switch override in the Product page card and click Save. Test again.
  3. Check that your theme updates the page address. Switch variants on your product page and watch the address bar. If ?variant= followed by a number changes each time, the generic script can follow it. If the address never changes, the generic script cannot help, so turn Variant switch override off again and go to the next step.
  4. Contact support. Open Support in EZ Preorder and send the product link and your theme name. Support can write and save a custom script for your theme. See How to get help and contact support.

What Variant switch override changes

Variant switch override in EZ Preorder saves the generic variant script, so EZ Preorder follows the ?variant= value in the page address instead of the Variant selector input.

  • The switch shows On whenever any custom script is saved, including a preset's script or one written by support.
  • Turning it off removes the saved script, whichever one it was. Turning it on again adds the generic script, not the previous one.
  • To get a preset's script back, choose the preset again in the Theme Selector. To get a support-written script back, contact support.

You cannot type or paste your own script. Custom JS is visible only to EZ Preorder support. More detail: How to use the advanced theme settings.

Common symptoms and fixes

The preorder button stays after switching to a variant that is not on preorder. EZ Preorder did not see the switch. Choose your theme preset, then try Variant switch override, then contact support.

Your normal add to cart button stays after switching to a preorder variant. EZ Preorder did not see the switch. Choose your theme preset, then try Variant switch override, then contact support.

After switching back, your theme's add to cart button does not come back, or the wrong button comes back. EZ Preorder cannot find your theme's original button again. Choose your theme preset. If your Submit button selector of add to cart form does not include type="submit", contact support about turning on Add 'type' attribute to button.

Two preorder buttons, or a preorder button and an add to cart button, show at once. Your theme may have a second product form on the page, such as a sticky add to cart bar or a Featured product section. Contact support so the selectors can target the right form.

It worked until I chose a preset or clicked Reset to default selectors. Both replace any saved custom script, including one support wrote for you. Contact support to have it added again.

Turning on Variant switch override made it worse. Your theme probably does not put ?variant= in the page address. Turn Variant switch override off, click Save, and contact support.

Frequently asked questions

Why does the preorder button only update when I refresh the page?

Your theme changes the selected variant without telling EZ Preorder. Choose your theme preset or turn on Variant switch override in Configuration → Theme Settings.

Where is the Add snippet button?

It has been replaced. To add EZ Preorder's generic variant script, turn on Variant switch override in the Product page card of Theme Settings and click Save.

Can I paste my own JavaScript to fix variant switching?

No. Only EZ Preorder support can add or edit Custom JS. Contact support and they can write a script for your theme.

Can I turn Variant switch override off again?

Yes, at any time, by turning it off and clicking Save. Be careful when the switch is already on because of a preset or support: turning it off deletes that script, and turning it back on adds the generic script instead.

Does this affect stores on the Free plan?

Theme Settings, presets and Variant switch override are available on every plan, including Free.