Test App on Dev Store admin/oauth/authorize redirecting to partners.shopify.com

[shsp_jbn]

I have a test app and a dev store. In the beginning of the OAuth flow, when I try to redirect to the URL for "Showing the installation permissions prompt", I get immediately redirected to https://partners.shopify.com/. There's no intermediate route; the response from the aforementioned URL comes with a "location" header values with "https://partners.shopify.com/".

Previously, when I made other mistakes (e.g. provided "read_all_orders" without prior approval) I've received appropriate errors. But I haven't found anything concerning this one.

A big thanks in advance for any help with this issue.

Network activity after hitting "Install" in the "Test app on development store" page.

[shsp_jbn]

I don't know if this extra bit of context helps, but when this started happening I tried a few times in Incognito mode to avoid any sticky state. No effect unfortunately.

[shsp_jbn · Accepted solution]

As it turns out, the OAuth entry URL I was using was missing a pair of square brackets.

I was using

https://{shop}/admin/oauth/authorize?client_id={api_key}&scope={scopes}&redirect_uri={redirect_uri}&state={nonce}&grant_options=value

instead of

https://{shop}/admin/oauth/authorize?client_id={api_key}&scope={scopes}&redirect_uri={redirect_uri}&state={nonce}&grant_options[]=value

A big shout out to my team member, Geronimo! Another pair of eyes always adds extra clarity.