Internal Server Error invalid name: "Visitor UUID" running shopify theme dev local environment

Topic summary

Developers encounter an \

Summarized with AI on November 18. AI used: claude-sonnet-4-5-20250929.

I’m getting an Internal Servor Error with an error for invalid name: “Visitor UUID” when I try to run my local environment using shopify cli. I recently upgraded to shopify cli 3.45.1 but I was able to run my local environment previously with no issue.

Anyone experienced this or have any idea how to resolve?

Thanks

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I got the same problem upgrading to 3.46.4

I found the problem is the UUID cookie is getting cached. Go in your chrome developer tools to application and clear all the cookies to your localhost path

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“fantastic!”

Helpful! Thank you.

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Actually going to reply to my own solution as this isn’t an accepted solution and was once a solution. Clearing cookies is only temporary, Not matter what my team does we experience this on a daily basis to the point where we have to block all cookies and no longer can develop with any apps installed due to the cookies blocked just to use the CLI. On going problem!

It happens to me only on one store, which happens to be protected by a password. Not sure if it being protected by a password is related to the issue.

Update:

For me the error was:

Internal Server Error

invalid name: “beyours:promo-popup”

Which only happens while I’m developing locally.

Which refers to the name of a cookie used on theme we’re using (Be Yours) for some custom pop-up component:

So I added these lines as a workaround to skip this component while I’m working locally:

Update:

Finally found the root problem for our site, the Google Tag Manager script was creating the issue in our theme.liquid. I commented it out and everything went smoothly. Still not sure why yet as to why Google Tag Manager is passing along a bad tag or another app is picking up the tag and creating a bad cookie name “Visitor UUID” in our local environment.