SyliusAdminBundle:Crud - Unable to find a template

I'm trying to make my first Grid in Sylius.

https://sylius-older.readthedocs.io/en/latest/bundles/SyliusGridBundle/your_first_grid.html#generating-the-crud-routing

I created entity Supplier and SupplierInterface. Then created config/packages/resources.yaml file with following content:

sylius_resource:
    resources: 
        app.supplier: 
            classes:
                model: App\Entity\Supplier

Now I want to add a route for CRUD actions:

sylius_admin:
    resource: "@SyliusAdminBundle/Resources/config/routing.yml"
    prefix: '/%sylius_admin.path_name%'

sylius_paypal_admin:
    resource: "@SyliusPayPalPlugin/Resources/config/admin_routing.yml"
    prefix: '/%sylius_admin.path_name%'

app_supplier:
    resource: |
        alias: app.supplier
        section: admin
        templates: SyliusAdminBundle:Crud
        except: ['show']
        grid: app_admin_supplier
    type: sylius.resource
    prefix: /admin

but my /admin/suppliers/new shows me an error:

Unable to find template "SyliusAdminBundle:Crud:create.html.twig" (looked into: /var/www/html/vendor/knplabs/knp-menu/src/Knp/Menu/Resources/views, /var/www/html/templates, /var/www/html/templates, /var/www/html/vendor/symfony/twig-bridge/Resources/views/Form).

I had this same issue updating from 1.8 to 1.9.

Resolved it by changing the line

templates: SyliusAdminBundle:Crud

to

templates: "@SyliusAdmin\\Crud"

in your routes (under app_supplier in your case).