update and fields. The fields that can be set in the issue or subtask are determined using the  Get create issue metadata. These are the same fields that appear on the issue's create screen. Note that the description, environment, and any textarea type custom fields (multi-line text fields) take Atlassian Document Format content. Single line custom fields (textfield) accept a string and don't handle Atlassian Document Format content.issueType must be set to a subtask issue type (use  Get create issue metadata to find subtask issue types).parent must contain the ID or key of the parent issue.curl --location --request POST '/rest/api/3/issue' \
--header 'Content-Type: application/json' \
--data-raw '{
    "fields": {
        "assignee": {
            "id": "5b109f2e9729b51b54dc274d"
        },
        "components": [
            {
                "id": "10000"
            }
        ],
        "customfield_10000": "09/Jun/19",
        "customfield_20000": "06/Jul/19 3:25 PM",
        "customfield_30000": [
            "10000",
            "10002"
        ],
        "customfield_40000": {
            "content": [
                {
                    "content": [
                        {
                            "text": "Occurs on all orders",
                            "type": "text"
                        }
                    ],
                    "type": "paragraph"
                }
            ],
            "type": "doc",
            "version": 1
        },
        "customfield_50000": {
            "content": [
                {
                    "content": [
                        {
                            "text": "Could impact day-to-day work.",
                            "type": "text"
                        }
                    ],
                    "type": "paragraph"
                }
            ],
            "type": "doc",
            "version": 1
        },
        "customfield_60000": "jira-software-users",
        "customfield_70000": [
            "jira-administrators",
            "jira-software-users"
        ],
        "customfield_80000": {
            "value": "red"
        },
        "description": {
            "content": [
                {
                    "content": [
                        {
                            "text": "Order entry fails when selecting supplier.",
                            "type": "text"
                        }
                    ],
                    "type": "paragraph"
                }
            ],
            "type": "doc",
            "version": 1
        },
        "duedate": "2019-05-11",
        "environment": {
            "content": [
                {
                    "content": [
                        {
                            "text": "UAT",
                            "type": "text"
                        }
                    ],
                    "type": "paragraph"
                }
            ],
            "type": "doc",
            "version": 1
        },
        "fixVersions": [
            {
                "id": "10001"
            }
        ],
        "issuetype": {
            "id": "10000"
        },
        "labels": [
            "bugfix",
            "blitz_test"
        ],
        "parent": {
            "key": "PROJ-123"
        },
        "priority": {
            "id": "20000"
        },
        "project": {
            "id": "10000"
        },
        "reporter": {
            "id": "5b10a2844c20165700ede21g"
        },
        "security": {
            "id": "10000"
        },
        "summary": "Main order flow broken",
        "timetracking": {
            "originalEstimate": "10",
            "remainingEstimate": "5"
        },
        "versions": [
            {
                "id": "10000"
            }
        ]
    },
    "update": {}
}'{"id":"10000","key":"ED-24","self":"https://your-domain.atlassian.net/rest/api/3/issue/10000","transition":{"status":200,"errorCollection":{"errorMessages":[],"errors":{}}}}