Preview_theme link automatically added leads to error

This is a really urgent matter because we’re doing one of our best weeks revenue wise. We’re planning on sending new campaigns in 4 hours…

This morning our customer service sent me a link that she found in Google Search, leading to a landing page that ended with &preview_theme_id=188804137344.

It led to an error page, so I asked our SEA guy to investigate it. Have not seen an explanation yet. CS reported this also on the 8th of January already but we didn’t think it was that big of a deal.

This evening we sent our weekly campaigns.
The link placed behind the button is: https://xxx/discount/xxx?redirect=/collections/maaltijden
This link applies discount directly when the customer clicks it. This has always worked great for us without any redirect trouble until now.

What happened tonight is this:
Many people are calling us and telling us they’re landing on an error page that says the following:

Theme cannot be previewed because it’s missing one of these required files: layout/theme.liquid, config/settings_schema.json

the URL their on at this moment is this:

https://www.xxx.nl/collections/maaltijden?utm_source=Klaviyo&utm_medium=email&utm_campaign=%28WO%29+28+januari%3A+heractivatie+%2B9+weken&eyk_source=klaviyo&eyk_campaign=%28WO%29+28+januari%3A+heractivatie+%2B9+weken+%2801KG209QET37WJ1E0Y7WRRDHZ0%29&eyk_id=01KG209QET37WJ1E0Y7WRRDHZ0&_kx=H-uWmPcv8hhHX-i2L1LqIxZ0IIGwUtePCi3B1Ln4qE0.VLzxNQ&preview_theme_id=188804137344

The piece of URL that is causing the issue is &preview_theme_id=188804137344
When I remove this part out of the URL, the page is loading fine.

I have no idea why this is being added automatically, and when I turn “add parameters” off in Klaviyo, nothing changes.

This theme does not exist in our shop at this moment.

The people that land on the error page don’t have the issue when using incognito, so it also is something about cookies but we can’t tell our 80 year old customers to delete their cookie history.

This problem is occuring in Google since the beginning of January as far as we can tell, and this is the first time it occurred through Klaviyo but it’s big time.

Can you please help me find out what is causing this piece of URL to be automatically added to our links? We’re doing one of our best weeks in revenue over all time and we can’t have such an issue disrupt it.

Important to mention is that it’s only happening to some people, not all. It’s happening in Google and Klaviyo but that is as far as we now, could be happening in more places.

People keep telling me that it is in the link I placed behind the button in the email campaign, but it’s not…

I’d try to specify ?preview_theme_id= or ?preview_theme_id=XXX (where XXX is the id of your live theme) in the URLs you share.

Then it should direct your visitors to the actual live theme no matter what cookies they have at the moment.

Adding &pb=0 will disable the preview bar.

Your customer service agent needs to give you more context about what they actually searched in Google that surfaced that link. You can also use various SEO tools to identify backlinks to specific URLs on your site. Maybe you accidentally have a direct link to a page with preview_theme_id (most likely), or someone else is linking to that exact URL.