Error Messages Appear on Home Page After Updating Flexible Checkout Fields

I updated Flexible Checkout Fields just now, and I’m seeing error messages at the top of my site’s home page. I deactivated my plugins one by one, discovering that it’s Flexible Checkout Fields causing the error messages. So, I deactivated your plugins to keep the errors from showing to my site’s visitors. I still need the functionality of Flexible Checkout Fields, so I’m hoping you can provide a solution. I created a support ticket at WPdesk.net as well as here, since I’m not sure where to ask this question.

The errors that appear at the top of my site’s home page are as follows:

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Warning: call_user_func_array() expects parameter 1 to be a valid callback, first array member is not a valid class name or object in /home/deepurba/public_html/wp-includes/class-wp-hook.php on line 286

Warning: Cannot modify header information – headers already sent by (output started at /home/deepurba/public_html/wp-includes/class-wp-hook.php:286) in /home/deepurba/public_html/wp-content/plugins/sg-cachepress/class-sg-cachepress.php on line 315

Warning: Cannot modify header information – headers already sent by (output started at /home/deepurba/public_html/wp-includes/class-wp-hook.php:286) in /home/deepurba/public_html/wp-content/plugins/sg-cachepress/class-sg-cachepress.php on line 327

Warning: call_user_func_array() expects parameter 1 to be a valid callback, first array member is not a valid class name or object in /home/deepurba/public_html/wp-includes/class-wp-hook.php on line 286

Warning: call_user_func_array() expects parameter 1 to be a valid callback, first array member is not a valid class name or object in /home/deepurba/public_html/wp-includes/class-wp-hook.php on line 286

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Thank you!