Testing my UserEdit Api endpoint using swagger fails and throws a code 400 response

[HttpPut("Edit")]
public async Task<ActionResult> UserEdit([FromBody] UserModel user, string password)
{
    var retrievedEntity = _context.Users.Find(user.UserName);
    if (retrievedEntity == null) {
        return NotFound("User was not found in database");
    }
    
    bool changeApproved = Security.VerifyPassword(password, user.Password);
    if (!changeApproved) {
        return BadRequest("Wrong password");
    }

    var userEntity = UserServices.ModelToEntity(user);

    _context.Users.Update(userEntity);
    await _context.SaveChangesAsync();
    return Ok("User successfully updated");
}