Issue is assigned to random user when setting Assignee as "Unassigned" or null via REST API (Jira Da

[Raul Aguirre]

Hello,

We are facing an issue when creating issues via the Jira REST API in a Jira Data Center environment.

When trying to create an issue with the Assignee set as "Unassigned" or null (which is the value returned by the API when fetching an unassigned issue), Jira automatically assigns the issue to a random user who is not even part of the project.

This behavior is unexpected, as we would like the issue to remain unassigned.

---

Environment

• Jira: Data Center

• Creation method: REST API (/rest/api/2/issue)

• Authentication: Personal Access Token

• Issue type: Test / Standard Issue

• Assignee field: Enabled and available on create screen

---

Steps to Reproduce

1. Create an issue via REST API with the following payload:

{
"fields": {
"project": { "key": "PROJECTKEY" },
"summary": "Test issue",
"issuetype": { "name": "Test" },
"assignee": null
}
}

or

 {
"fields": {
"project": { "key": "PROJECTKEY" },
"summary": "Test issue",
"issuetype": { "name": "Test" },
"assignee": { "name": "Unassigned" }
}
}

2. Create the issue.

3. Check the assignee after creation.

---

Expected Result

The issue should be created as Unassigned, without any user assigned.

---

Actual Result

The issue is automatically assigned to a random user who is not part of the project.

---

Additional Information

• When retrieving an unassigned issue via GET, the API returns assignee: null.

• Passing this same value during creation does not preserve the unassigned state.

• The user assigned automatically is not related to the project permissions.

• This behavior affects automation and integrations.

[Raul Aguirre · Accepted solution]

We identified that the project default assignee is set to Project Lead, which explains the behavior.
When issues are created with assignee null, Jira automatically assigns them to the project lead.
Thank you for the guidance.

[Duc Thang TRAN]

Hello @Raul Aguirre 

Here’s what I’m currently using in Jira Data Center as JSON.

{

  "fields": {

    "project": {

      "key": "GtestR"

    },

    "summary": "sommaire d'un test",

    "issuetype": {

      "id": "10116"

    },

    "assignee": null

  }

}

Do you have any automation that can assign tickets to a group of users, with options like random assignment or round-robin?

Also, what is the permission scheme for your project (especially the Assignable User permission)? Other users need this permission to be able to assign tickets in your project.

I didn’t see any component field in your JSON, but that might be another angle worth checking.

[Trudy Claspill]

Hello @Raul Aguirre 

What version of Jira are you using?

Have you tried simply not including assignee in the payload?

(I don't currently have access to a Data Center environment to test this out, but I will give it a try in a couple of days if somebody else has not already identified the solution.)

[Raul Aguirre]

Hello, @Trudy Claspill

I'm using Jira Data Center v9.12.30, and yes, I have already tried not sending the Assignee field at all in the payload when creating the issue via REST API.
However, the issue still gets automatically assigned to a user instead of remaining Unassigned.

Please let me know if there is any recommended approach or configuration to ensure issues are created as Unassigned via the API in this Jira version.

Thank you.

[Trudy Claspill]

I have not yet been able to test this against a Jira DC system to see if I can reproduce it.

When you review the issue history for issues created through the API, do you see an entry for the Assignee being set? If so, does the timestamp match the Creation timestamp or is it a bit later? And who is shown as responsible for changing the Assignee field?

Does this happen regardless of which project you target?

Is the target project a Software project or Service project?