Hi @_Moooov! In my experience the error you’re seeing happens when there’s a mismatch between your app’s installation flow configuration and what the automated checker expects.
By default (when use_legacy_install_flow is omitted or set to false in your shopify.app.toml), Shopify uses managed installation - meaning Shopify handles the install process without calling your app’s OAuth callback at all. It looks like the checker then expects your app to load directly after install, but instead your app is trying to kick off the legacy OAuth grant flow, which causes that redirect to /app/grant.
You have two options:
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Switch to Shopify managed installation with token exchange (recommended for embedded apps). This eliminates the OAuth redirects entirely - your app loads directly after install and uses session tokens to get access tokens on demand.
-
If you need the legacy OAuth flow for some reason, set
use_legacy_install_flow = truein your TOML file and runshopify app deploy. This tells Shopify to call your callback during installation.
For embedded apps, option 1 is the way to go. This thread had the exact same issue and resolved it by switching to managed installation.