Upgrading to any UI Extension API that uses web components now enforces a 64kb bundle size as seen here: Upgrading to 2025-10 This is a very unexpected and breaking change, specially for apps whose core features are deeply integrated as UI Extensions. The expectation to go from a 2MB limit to 64kb…

@muchisx Just my 3c: I spent quite some time (and tokens) figuring out the Sentry integration. You can get it working with simpler extensions, but there’s a fundamental problem with Shopify itself - thrown errors just lack full context. Just wanted to let you know that there isn’t much value in runn…

Hi @Patrick_Jakubik Thanks for your feedback! We mostly use Sentry to report back on our own captured exceptions and full tracing on complex conditional flows, the global error Sentry capture is indeed lacking a lot

Hi @Robin-Shopify , thanks again for the follow up. The base bundle of a clean-slate extension generated via shopify app generate extension is already around 21 KB, without adding any real application code beyond the default template. I tested this with a Customer Account extension. That effective…

Hey everyone, just jumping in to strongly back up @muchisx on this. Look, we all know Shopify is pushing hard for better performance and faster load times. We completely respect that. But dropping from a 2MB limit down to a hard 64KB cap—a nearly 97% reduction—just ignores the reality of building …

Thanks everyone, please keep this kind of feedback coming. Just a few things: @muchisx I don’t intent to invalidate anything you’re saying, but let’s make sure to compare apples with apples or compressed with compressed. For example, a newly generated checkout extension clocks in at ~8.5k gzippe…

I also agree with the group here. These limits may work for custom checkout extensions where everything is static and has a single use case. But when building extensions that need to support multiple use cases for different merchants needs, based on their industry it requires our extensions to be mo…

No worries @Robin-Shopify !, it’s all well taken! Our numbers, including the exercise of generating a new customer account extension and seeing 21kb (not checkout) come from the actual file size of the generated /dist/file.js bundle when running shopify app build. I’m not aware of any other techniq…

I’m not aware of any other technique to see further compression on that file. Got it! I suppose how to do that exactly depends on your operating system, but on macOS for example, you should be able to do: gzip -c /dist/file.js | wc -c

Here’s with the approach suggested in the docs , i’m on Windows: Steps: shopify app init shopify app generate extension Choose a Customer Account UI extension shopify app build Pass the generated metafile.json into: esbuild - Bundle Size Analyzer [image] [image]

The bundle analyzer unfortunately doesn’t show compressed sizes. It helps finding large dependencies and files, but doesn’t show the full picture.

Reconsider recent UI Extensions file size limit changes

Extensions

derrick July 2, 2026, 4:41pm 28

I believe I saw that Shopify is extending until October 1st, 2026 for migration to 2025-10.

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Reconsider recent UI Extensions file size limit changes

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