Shopify Customer Account Authentication Woes: From Localhost to Production Disaster!

Decoding the "Verkeerde redirect_uri" Error: A Shopify Authentication Saga

Ever banged your head against the wall trying to get Shopify Customer Accounts authentication working smoothly? You're not alone! Recently, a developer named Zeeper ran into a particularly frustrating issue, and their detailed post in the Shopify community sparked some helpful insights. Let's break down the problem and see what we can learn.

The Problem: Localhost Lingers in Production

Zeeper was building a Shopify app with a theme app extension that used Shopify Customer Accounts OAuth for authentication. Everything worked perfectly in their development environment (using localhost), but when they deployed to production on Fly.io, disaster struck. The OAuth request was still stubbornly using redirect_uri = https://localhost:3458/auth/callback, leading to a "Verkeerde redirect_uri" error (Dutch for "Incorrect redirect_uri"). Ouch!

Here's the core issue:

"The main problem is not that localhost remains registered somewhere, but that if I change it to my App address, all account services simply stop working, both on DEV and on PROD"

They'd already tried the obvious fixes:

• Updating frontend and backend configurations to use the production domain.
• Explicitly configuring multiple redirect URLs in shopify.app.toml.

Despite all this, the OAuth request in production still used localhost. Frustrating, right?

Digging Deeper: Potential Culprits and Solutions

So, what could be causing this persistent localhost issue? Zeeper raised some excellent questions:

• Is there a hidden default in Shopify CLI?
• Is a deploy/sync step required for redirect URIs?
• Is there a common Fly.io / environment variable pitfall?
• Is there something specific to Customer Accounts MCP auth that I’m missing?

While the community thread didn't offer a definitive solution *yet*, it highlights some important areas to investigate when you encounter this kind of problem:

1. Double-check your environment variables. It sounds obvious, but it's easy to miss a stray .env file or a misconfigured variable in your deployment platform (like Fly.io). Make absolutely sure that REDIRECT_URL and any other relevant variables are correctly set to your production domain.

2. Inspect your OAuth request. Use your browser's developer tools to examine the actual OAuth request being sent from your production environment. This will confirm whether the redirect_uri is indeed localhost and help you pinpoint where it's being generated.

3. Clear your Shopify app's cache. Sometimes, Shopify's app platform can cache old configurations. Try uninstalling and reinstalling your app on the production store to clear any cached data.

4. Review your Shopify CLI configuration. Although Zeeper explicitly configured redirect URLs in shopify.app.toml, it's worth checking your global Shopify CLI configuration for any conflicting settings. Look for any .shopify or .config files that might be overriding your app-specific settings.

5. Consider the order of operations. Ensure that you're setting the redirect URI *before* initiating the OAuth flow. If you're setting it asynchronously or after the flow has already started, it might not be applied correctly.

6. Shopify Partners Dashboard Configuration: Even if your app is installed, verify the allowed redirect URLs in the Shopify Partners Dashboard under your app's settings. It's an easy step to overlook.

Code Example: shopify.app.toml

Zeeper mentioned their shopify.app.toml file. For reference, here's what that configuration might look like:

# shopify.app.toml

name = "Your App Name"
client_id = "YOUR_CLIENT_ID"
client_secret = "YOUR_CLIENT_SECRET"

[access_scopes]
 scopes = "customer-account-mcp-api:full"

[application_url]
 url = "https://your-fly-app.fly.dev"

[auth]
redirect_urls = [
 "https://your-fly-app.fly.dev/auth/callback",
 "https://your-fly-app.fly.dev/auth/shopify/callback",
 "https://your-fly-app.fly.dev/api/auth/callback"
]

Remember to replace YOUR_CLIENT_ID, YOUR_CLIENT_SECRET, and your-fly-app.fly.dev with your actual values.

It's a tricky situation, and these authentication issues can really slow you down. While there wasn't a single definitive answer in this particular thread, the key takeaway is to meticulously check your configurations, environment variables, and OAuth requests. Good luck debugging, and remember the Shopify Community is there to help if you get stuck!