**Steps to replicate the issue** (include links if applicable):
* `git clone https://gitlab.wikimedia.org/repos/m3api/m3api-examples.git`
* `cd m3api-examples/webapp-clientside-vite-guestbook`
* `npm install`
* `npm run start`
* go to http://localhost:8080/
* log in via OAuth
* click the “sign guestbook” button
Alternatively, use the webapp-//clientside//-vite-guestbook instead (`with `npm run dev` as the command to launch it).
**What happens?**:
The API request fails with HTTP status 401 and the JSON contents:
```lang=json
{
"httpCode": 401,
"httpReason": "Jwt issuer is not configured"
}
```
**What should have happened instead?**:
OAuth 2 should work.
**Software version** (on `Special:Version` page; skip for WMF-hosted wikis like Wikipedia):
Current 1.46.0-wmf.16
**Other information** (browser name/version, screenshots, etc.):
@Reedy suspects this is related to T417820 / T417278 / T261462.
@Arcstur and Vincent on Telegram have also reported encountering this issue.