failed: Permission denied (13) Error when loading page in browser

Hi all,

I have just started working with a new theme and it was going great until I tried viewing the site from another device.

I am working in google chrome logged in as admin to the WP back end. I am able to work on the site and view it without any issues.

The page throws up an error when I try to view on the following:

My smartphone
internet explorer on my computer
internet explorer and firefox on a different computer

The error is as follows:

Warning: session_start(): open(/tmp/sess_bc2679a6f8bb54e0289e5e7efc8a612d, O_RDWR) failed: Permission denied (13) in /home/floor723/public_html/wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php on line 54

Warning: session_start(): Cannot send session cookie – headers already sent by (output started at /home/floor723/public_html/wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php:54) in /home/floor723/public_html/wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php on line 54

Warning: session_start(): Cannot send session cache limiter – headers already sent (output started at /home/floor723/public_html/wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php:54) in /home/floor723/public_html/wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php on line 54

Warning: Cannot modify header information – headers already sent by (output started at /home/floor723/public_html/wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php:54) in /home/floor723/public_html/wp-includes/pluggable.php on line 1173

Warning: Unknown: open(/tmp/sess_bc2679a6f8bb54e0289e5e7efc8a612d, O_RDWR) failed: Permission denied (13) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0

It initially threw up this error about a different ‘non critical’ plugin which i disabled. It then started complaining about the YITH Wishlist plugin. Which I cant disable as it is critical to my themes requirements apparently.

I have not made any modifications to the themes PHP structure as I am not particularly PHP savvy.

When I switched to my present theme i used a plugin to reset the database as per my new themes instructions, not sure if that could have caused it but i thought was worth a mention.

If anybody could offer any assistance I would really appreciate it as I am rather stumped!

Thanks