Found bugs with so many errors log

Dear.

I see so many error on my hosting log. like :

#The The “add_to_cart_fragments” hook uses out of date data structures and function is deprecated since version 3.1.2. Replace with woocommerce_add_to_cart_fragments.

#PHP Warning: Illegal string offset ‘tour_phys’ in /home/***/public_html/wp-content/plugins/travel-booking/inc/widgets.php on line 43

#PHP Warning: Illegal string offset ‘pa_bulan’ in /home/***/public_html/wp-content/plugins/travel-booking/inc/widgets.php on line 63

#PHP Warning: Illegal string offset ‘pa_tujuan’ in /home/***/public_html/wp-content/plugins/travel-booking/inc/widgets.php on line 63

#The The “add_to_cart_fragments” hook uses out of date data structures and function is deprecated since version 3.2.0. Replace with woocommerce_add_to_cart_fragments.

#PHP Warning: Illegal string offset ‘tour_phys’ in /home/***/public_html/wp-content/plugins/travel-booking/inc/widgets.php on line 68

#PHP Warning: Illegal string offset ‘pa_bulan’ in /home/***/public_html/wp-content/plugins/travel-booking/inc/widgets.php on line 88

#PHP Warning: Illegal string offset ‘pa_tujuan’ in /home/***/public_html/wp-content/plugins/travel-booking/inc/widgets.php on line 88

There so many logs with same errors..
Please fix it.

I try to change the PHP Version from 5.6 to 7.1
but still got same error.

Thank you