Azure Portal won't let me create a subscription to an Azure event grid topic. Create button greyed out

Question

Ok really basic - I can't seem to create a subscription to an Azure event grid topic in the Azure Portal. Followed the guides and there is no red ink (to indicate any errors or anything I've missed) in the form but the "Create" button remains steadfastly grey and unreactive to my increasingly desperate presses!

So using "Create Event Subscription" Form on the Azure Portal and...

1. Subscription name is correctly formatted.
2. Topic has ben correctly generated (in fact its pre-filled) as I'm choosing the create option from the event topic. Topic is active.
3. Endpoint is valid - I selected it from drop downs that only show functions which are event grid triggers so doesn't look like I could select any endpoint that wasn't. I created the function specifically to test the trigger.

Obviously missing something very basic but the form is giving no clue as to what it is.

Only thoughts are:

1. I haven't specified an event type filter but as far as I'm aware it defaults to all which is why the online guide makes no mention of this option.
2. The function I've created doesn't do anything but I can't see why that would stop it being triggered and thus being a valid endpoint.

I'm at a loss. I've included the json for the attempted subscription shown in the advanced editor if that provides any clues...

{
"name": "testeventsub",
"properties": {
    "topic": "/subscriptions/xxxxxxxxxx/resourceGroups/DBProject/providers/Microsoft.EventGrid/topics/filings",
    "destination": {
        "endpointType": "AzureFunction",
        "properties": {
            "resourceId": "/subscriptions/xxxxxxxxxxx/resourceGroups/DBProject/providers/Microsoft.Web/sites/FilingTestEventTrigger1/functions/NewFilingTrigger1",
            "maxEventsPerBatch": 1,
            "preferredBatchSizeInKilobytes": 64
        }
    },
    "filter": {
        "advancedFilters": []
    },
    "labels": [],
    "eventDeliverySchema": "EventGridSchema"
}

}

Answer 1

I was having same issue. To solve it, I went to the "search" Azure option at the top of the browser, and I searched for "Event Grid Subscriptions", then I selected "Event Grid Subscriptions":

Then, when the view is open, I select the option: "+ Event Subscription":

That allows me to create the subscription, after being filled up anything I need:

Answer 2

I have do a test, and I face the problem as same as same as you describe:

I also face the Create button greyed out. This problem only comes when you try to create event grid subscription under the event grid topic service.

But you can directly create event grid subscription under the event grid subscription service.

This is the json format on my side:

{
    "name": "0308bowman2",
    "properties": {
        "topic": "/subscriptions/xxxxxx/resourceGroups/testtopic/providers/Microsoft.EventGrid/Topics/testtopic",
        "destination": {
            "endpointType": "AzureFunction",
            "properties": {
                "resourceId": "/subscriptions/xxxxxx/resourceGroups/0730BowmanWindow/providers/Microsoft.Web/sites/0308bowman/functions/EventGridTrigger1",
                "maxEventsPerBatch": 1,
                "preferredBatchSizeInKilobytes": 64
            }
        },
        "filter": {
            "advancedFilters": []
        },
        "labels": [],
        "eventDeliverySchema": "EventGridSchema"
    }
}

This can create success, but I think it is not enough. If we look at the integration mode of event grid subscription and other services, we can find we need to provide event type and subject filters(I didn't do something like event topic&event subcription. But taking integration with other services as examples, I think this is necessary.).

Therefore, for the problem of graying out the Create button, I think this is a front-end bug of azure portal, and this is not your problem.