wordpress woocomerce subscriptions and Membership error


I am adding the custom code in the function create_subscription ()

here is the code which gives the error ,,,I have mentioned in comments which line gives the error

$  renewal = wcs_order_contains_renewal($  parent_order->get_id());         if ($  renewal == false) {             if ($  trial_length > 0) {                 $  dates = array(                     'trial_end' => $  next_payment,                     'next_payment' => $  next_payment,                 );                 try {                     $  subscription->update_dates($  dates); //this code line gives the error it works fine if I comment this line                 } catch (\Exception $  e) {                     f24_write_data_to_file('Error in updating Trial end date ');                     f24_write_data_to_file($  dates);                 }              }         }         \WC_Subscriptions_Manager::activate_subscriptions_for_order($  parent_order);          $  this->subscription = $  subscription;          // On order created.         do_action('paywall/wc_subscription_created', $  subscription);          return $  subscription; 

and here is the error which I got ,,, I am using the woocommerce subscriptions plugin and Woocommerce Membership Plugin, Need help now, how to fix the error while updating the trial_end date?

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