I have extended the REST API as described in the official documentation, and I can access my newly created API route from my frontend siteaccess, so e.g.
When I call the same route from the legacy backend
I get a kernel(20) error page.
The default REST API routes provided by eZ Publish out of the box work, so e.g.
both return the expected result.
I would like to be able to access my custom REST API from the legacy backend, too.