Error while creating list item with multi-user field - pnp js / spfx

Question

In my spfx webpart, I'm creating list item using pnp js. As per pnp-core-js documentation I have written following code, but its failing with error.

Private AddListItem()
{
    pnp.sp.web.lists.getByTitle('EmployeeList').items.add({
    JobTitle : this.state.var_JobTitle,
    JobDescription :this.state.var_JobDescription,
    Salary:this.state.var_Salary,
    Age:this.state.var_Age,
    LocationId:this.state.var_Location.key,
    Technology:this.state.var_Technology.key,
    Passport:this.state.var_Passport,
    ManagerId:{results:[15,29]}
    }).then((iar:pnp.ItemAddResult)=> {
    console.log(iar);
    });
}

Error:

Error: Error making HttpClient request in queryable [400]  ::> {"odata.error":{"code":"-1, Microsoft.SharePoint.Client.InvalidClientQueryException","message":{"lang":"en-US","value":"A node of type 'StartArray' was read from the JSON reader when trying to read a value of a property; however, a 'PrimitiveValue' or 'StartObject' node was expected."}}}

NOTE: If I comment that line (ManagerId) then code works fine.

Answer 1

Code looks fine.

1) Just ensure that you are using the correct internal name of the column.

2) Secondly, ensure that you have set the column to Allow multiple values as below. This error usually occurs when you try to update the column when this setting not present and only allows a single user value :