Curl "(6) Could not resolve host: http" - elasticsearch

Question

I am trying to run this command
curl -XPUT -H "Content-Type: application/json" https://localhost:9200/_all/_settings -d '{"index.blocks.read_only_allow_delete": null}'
But this results in this error
curl: (6) Could not resolve host: http
curl: (3) unmatched close brace/bracket in URL position 5:
null}'
I got this command from here
https://stackoverflow.com/a/50609418/3259896
I'm am not yet very familiar with curl nor elasticseach, so I'm not sure how to pinpoint the error
If it makes a difference, I am using Windows.
I also tried
$ curl -X PUT -H "Content-Type: application/json" https://localhost:9200/_all/_settings -d '{"index.blocks.read_only_allow_delete": null}'
Edit2:
I tried
curl -XPUT -H "Content-Type: application/json" http://localhost:9200/_all/_settings -d '{"index.blocks.read_only_allow_delete": null}'
But now get this error
{"error":{"root_cause":[{"type":"json_parse_exception","reason":"Unexpected character (''' (code 39)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput#446f2dd5; line: 1, column: 2]"}],"type":"json_parse_exception","reason":"Unexpected character (''' (code 39)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput#446f2dd5; line: 1, column: 2]"},"status":400}curl: (3) unmatched close brace/bracket in URL position 5:
null}'
^
I then tried
curl -XPUT -H "Content-Type: application/json" http://localhost:9200/_all/_settings -d "{"index.blocks.read_only_allow_delete": null}"
And I got
{"error":{"root_cause":[{"type":"json_parse_exception","reason":"Unexpected character ('i' (code 105)): was expecting double-quote to start field name\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput#696b36d3; line: 1, column: 3]"}],"type":"json_parse_exception","reason":"Unexpected character ('i' (code 105)): was expecting double-quote to start field name\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput#696b36d3; line: 1, column: 3]"},"status":400}

Answer 1

First off, in that other SO question, the ES node was a live one so its URL included https.
Your localhost ist almost certainly not going to have https so change it to http:
curl -XPUT -H "Content-Type: application/json" \
http://localhost:9200/_all/_settings \
-d '{"index.blocks.read_only_allow_delete": null}'
Other than that, everything looks okay, provided that your ES is running.
When successful, you should receive a simple message:
{"acknowledged":true}
Edit: go with
curl -XPUT -H "Content-Type: application/json" http://localhost:9200/_all/_settings -d "{\"index.blocks.read_only_allow_delete\": null}"