Razor component with async method in foreach loop

I'm trying to have a razor component in a foreach loop. this razor component has a async method call in it's OnInitializedAsync override method.

@foreach (var user in users)
{
    <span> @user.Email </span>
    <span> - </span>
    <span> @user.FullName </span>
    <button @onclick = "@(e => DeleteUser(user.Id))" > delete </button>
    <button @onclick = "@(e => showEdit(user.Id))" > edit </button>
    <UserRoles UserId = "@user.Id" />
    <br />
}

UserRoles.razor

protected override async Task OnInitializedAsync()
{
    userRoles = await _userService.GetRoles(UserId);
    StateHasChanged();
}

UserService.cs

public async Task<IList<string>> GetRoles(string userId)
{
    var user = await _UserManager.FindByIdAsync(userId);
    return await _UserManager.GetRolesAsync(user);
}

I'm getting following error

InvalidOperationException: A second operation started on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
    Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.EnterCriticalSection()
    Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable<T>+AsyncEnumerator.MoveNextAsync()
    Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync<TSource>(IQueryable<TSource> source, CancellationToken cancellationToken)
    Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync<TSource>(IQueryable<TSource> source, CancellationToken cancellationToken)
    Microsoft.AspNetCore.Identity.EntityFrameworkCore.UserStore<TUser, TRole, TContext, TKey, TUserClaim, TUserRole, TUserLogin, TUserToken, TRoleClaim>.GetRolesAsync(TUser user, CancellationToken cancellationToken)
    Microsoft.AspNetCore.Identity.UserManager<TUser>.GetRolesAsync(TUser user)
    Core.Services.UserService.GetRoles(string userId) in UserService.cs
    +
        return await _UserManager.GetRolesAsync(user);
    PersianFlac.Shared.UserRoles.OnInitializedAsync() in UserRoles.razor
    +
        userRoles = await _userService.GetRoles(UserId);
    Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
    Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

If there's only one user(foreach loop once) no error occurs.