Mysql error when I am trying to checkout

When I am trying to checkout with two different products in my cart, lets say tier1 and tier2 I get the following error at the errors-log of my site.

WordPress database error Incorrect datetime value: ‘0’ for column demo.sub_end_date.sub_end at row 1 for query INSERT INTO wp_postmeta (post_id, meta_key, meta_value) VALUES (3359, ‘_schedule_end’, ‘0’)

Any ideas why and how to fix it. Any suggestions would be appreciated. Thank you

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