Why is my app proxy causing a 404 error?

[GJJO]

My Ajax fetch call from the extension app is giving 404. It was working and changed proxy subpath and it started giving 404 error.

I have route and put the middleware to see any route mismatch. But nothing is called to backend from Shopify. Also, I have checked the route by calling the URL directly in the browser and it's hitting the server, so no issue with the server setup.

Any help would be appreciated from the Shopify team. 

[betelgeus · Accepted solution]

We have a similar issue. On a couple of stores the app proxi returns 404, while on the other works fine. 

We suspect that another app installed on that store uses the same app proxi as us, and the requests end up to the other app rather than us. 

Shopify must enforce uniqueness on the app proxi. 

[GJJO]

My issue and resolution are related to how Shopify handles the proxy setup. I have used the "Subpath" same for a couple of apps and ended up getting updated by Shopify differently.

The best place to look at this is - "App Proxy URL" in the About section of the App installed on the store.

I Hope, this will help others to troubleshoot.