Next.js Images Broken? OpenNext.js Cloudflare `localPatterns` Fix

Hey there, fellow developers! Ever hit that frustrating moment when your images, which were working perfectly fine, suddenly decide to go on strike after an update? If you're using OpenNext.js with Cloudflare and recently upgraded to @opennextjs/cloudflare version 1.14.x, you might be staring down a particularly nasty error: TypeError: localPatterns is not iterable. Trust me, you're not alone, and it's a real head-scratcher when your users are seeing broken image icons instead of your beautiful content. This issue specifically rears its ugly head when Next.js tries to process images through the Cloudflare worker, resulting in a dreaded 500 Internal Server Error and leaving your site looking, well, a little empty. Let's dive deep into what's causing this problem, how to spot it, and more importantly, how to fix it and get those pixels flowing again. We'll explore everything from pinpointing the exact error in your server logs to practical workarounds and long-term solutions, ensuring your image delivery pipeline on Cloudflare is robust and error-free.

Understanding the TypeError: localPatterns is not iterable Bug

Alright, guys, let's talk about this pesky TypeError: localPatterns is not iterable bug that's been messing with our OpenNext.js Cloudflare deployments. Essentially, this error pops up when the @opennextjs/cloudflare package, specifically in versions 1.14.x and above, expects a particular piece of configuration data – localPatterns – to be something it can loop through, like an array or a list. But for some reason, it's not getting that. Instead, it might be receiving undefined, null, or just a plain old single value that isn't iterable, causing the whole process to crash. Think of it like trying to read a shopping list, but someone handed you a single banana instead of a list – you can't iterate over a banana! This technical hiccup specifically impacts how Next.js images are processed and served when deployed to Cloudflare Workers, meaning your sleek Image components are just throwing 500 Internal Server Error responses back at the browser. This isn't just a minor glitch; it's a critical showstopper that prevents any images from loading, significantly degrading the user experience and potentially hurting your site's credibility. The broken images are a glaring symptom of a deeper compatibility or configuration issue that surfaced after the update. We’ve noticed this problem particularly after updating from 1.13.1 to the newer 1.14.x versions, indicating a change in how the package expects image configurations to be handled.

When we look at the server-side error message, we see the trail leading to hasLocalMatch and validateUrlQueryParameter within images.js. This images.js file is a crucial part of the Cloudflare worker that OpenNext.js generates, responsible for intercepting and handling image requests. It's where the logic for validating image URLs, optimizing them, and serving them efficiently lives. So, when localPatterns isn't iterable here, it means the worker can't properly determine if an incoming image request matches a locally defined pattern, which is essential for security and correct image routing. This failure in the image processing pipeline is why you're getting those ugly 500 errors for every image request. Understanding that this error originates from an expectation mismatch within the image handling logic of the Cloudflare worker is key to troubleshooting. The jump from 1.13.1 to 1.14.x clearly introduced a new expectation or changed the default behavior regarding how image domain patterns are structured or accessed, making previously working setups suddenly incompatible.

Replicating the Image Loading Issue: A Step-by-Step Guide

Alright, let's get down to brass tacks and figure out how to consistently reproduce this Next.js image loading issue. The good news, if you can call it that, is that it’s incredibly straightforward to trigger this bug, which makes it easier to test fixes. All you really need is a basic Next.js Image component being used in your application, deployed via OpenNext.js to Cloudflare. You don’t need any fancy configurations or complex setups; a simple image render is enough to expose the problem. This highlights how fundamental the issue is, affecting even the most common use cases of image display. The TypeError: localPatterns is not iterable error will consistently appear in your server logs, signaling that something is fundamentally broken in the image pipeline.

Consider this super common code snippet for displaying an image:

<Image
  src="/images/category/pic.png"
  alt="A beautiful picture of a category"
/>

This is about as basic image usage as it gets, right? You've got your src pointing to an image in your public directory, and an alt attribute for accessibility. Nothing controversial here. Yet, with @opennextjs/cloudflare versions 1.14.x and up, as soon as your browser tries to fetch this image from your deployed Cloudflare Worker, you’ll be greeted with a miserable 500 Internal Server Error. On the server side, where your Cloudflare worker is running, you'll see the tell-tale error message in your logs. Let's break down that stack trace, because it gives us huge clues about the server-side error:

TypeError: localPatterns is not iterable
    at hasLocalMatch (file:///path/to/repo/.open-next/cloudflare/images.js:464:30)
    at validateUrlQueryParameter (file:///path/to/repo/.open-next/cloudflare/images.js:345:12)
    at parseImageRequest (file:///path/to/repo/.open-next/cloudflare/images.js:273:28)
    at handleImageRequest (file:///path/to/repo/.open-next/cloudflare/images.js:80:23)
    at null.<anonymous> (file:///path/to/repo/.open-next/worker.js:38:30)
    at runWithCloudflareRequestContext (file:///path/to/repo/.open-next/cloudflare/init.js:13:31)
    at Object.fetch (file:///path/to/repo/.open-next/worker.js:17:16)

See those lines? hasLocalMatch and validateUrlQueryParameter are right there at the top of the stack. This means the problem originates deep within the image validation logic. Specifically, hasLocalMatch is trying to do its job – likely checking if the requested image URL matches any patterns defined for local images – but it's failing because whatever localPatterns is supposed to be, it's not a list it can iterate over. This is a critical piece of information for our stack trace analysis, guiding us towards the exact point of failure. The expectation, and rightly so, is that even without the cloudflare image binding configuration, images should just work. This bug represents a significant regression from previous versions where this basic functionality was a given. The fact that a straightforward image component breaks down with such an error indicates a fundamental change in how the newer opennextjs/cloudflare package processes image requests, making it incompatible with existing default Next.js setups unless specific actions are taken. This unexpected behavior is why so many developers are scratching their heads when their images suddenly stop loading.

Diving Deeper: Why localPatterns is not iterable?

Alright, let’s put on our detective hats and dig into the technical root cause analysis of this TypeError: localPatterns is not iterable error. From the looks of it, this issue likely stems from a significant change in how @opennextjs/cloudflare version 1.14.x (and higher) handles image configurations. Specifically, it seems that the localPatterns variable, which is critical for validating image URLs, is somehow not being initialized correctly or is being assigned a non-iterable value. In JavaScript, an