Notion API "[400] 0 is not a property that exists." while updating multi-select tag

Hi everybody,
first post in the community, so I’ll try to provide a clear picture…

My goal is to keep consistent tags’ names and colours between two databases in Notion.
I’ve tried many solutions using the “Create a database item” module, but I wasn’t able to map the colour (the name was easy).

So I tried to use the “Make an API call” module, but I’m no programmer…
After several trial-and-error attempts, it looks like I managed to provide the correct JSON code (via the “Create JSON” module) to the API call module, but now I get another error: “[400] 0 is not a property that exists.”

This is how the test scenario is set:

  1. Webhook as trigger
  2. search the source database in notion (for a specific checkbox marking any change in the record)
  3. create the new database item in destination database (including tags)
  4. create JSON
  5. update the tags’ values in the destination scenario

Here’s the overall scenario:

Here’s the error I get:

I’ve tried to recreate the bundle with the Create JSON module:

Here’s the OUTPUT of the “Create JSON” module:

[
    {
        "json": "{\"id\":\"dbfe499a-e08a-4fa8-84f1-95e8799b0311\",\"object\":\"page\",\"parent\":{\"type\":\"database_id\",\"database_id\":\"237bee2c-808a-4592-b1ca-f4b627399c68\"},\"properties\":[{\"multi_select\":[{\"id\":\"4880ab00-4103-4c57-aef1-a57ae060f3ad\",\"name\":\"blu\",\"color\":\"blue\"}]}]}"
    }
]

NOTE: the tags’ “id” is taken from the new item in the destination database, while “name” and “color” are taken from the source database.

I then put the JSON output in the body of the API call (and I believe that here I’m doing something very wrong…):

Here’s the “Make API call” INPUT:

[
    {
        "url": "/v1/pages/",
        "body": "{\"id\":\"665d4c94-a9ea-4b91-88aa-d661c20ce22c\",\"object\":\"page\",\"parent\":{\"type\":\"database_id\",\"database_id\":\"237bee2c-808a-4592-b1ca-f4b627399c68\"},\"properties\":[{\"multi_select\":[{\"id\":\"4880ab00-4103-4c57-aef1-a57ae060f3ad\",\"name\":\"blu\",\"color\":\"blue\"}]}]}",
        "method": "POST",
        "headers": [
            {
                "key": "Content-Type",
                "value": "application/json"
            }
        ],
        "version": "2021-08-16"
    }
]

And here’s the OUTPUT…

[
    null
]

I’m pretty sure I’m doing something very wrong with the JSON/API call, but do not know exactly what…

Any help is very much appreciated!