Getting following erroes in system.log magento 2.2.1 after upgrade to 2.1.9

Question

We are getting following errors continuously on magento 2.2.1 after upgrade to 2.1.9 in var/log/system.log file.

Can anybuddy facing same ?

[2018-01-22 10:04:12] main.INFO: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2018-01-22 10:04:12] main.INFO: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2018-01-22 10:04:12] main.INFO: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2018-01-22 10:04:12] main.INFO: Broken reference: the 'shopbybrand.block.sidebar' element cannot be added as child to 'sidebar.main', because the latter doesn't exist [] []
[2018-01-22 10:04:12] main.INFO: Broken reference: the 'wp.sidebar' element cannot be added as child to 'sidebar.main', because the latter doesn't exist [] []
[2018-01-22 10:04:12] main.INFO: Broken reference: the 'shopbybrand.block.sidebar' tries to reorder itself towards '', but their parents are different: 'sidebar.main' and '' respectively. [] []
[2018-01-22 10:04:12] main.INFO: Broken reference: the 'wp.sidebar' tries to reorder itself towards '', but their parents are different: 'sidebar.main' and '' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'shopbybrand.block.sidebar' element cannot be added as child to 'sidebar.main', because the latter doesn't exist [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.info.feed.sec' element cannot be added as child to 'content.top.most', because the latter doesn't exist [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'shopbybrand.block.sidebar' tries to reorder itself towards '', but their parents are different: 'sidebar.main' and '' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.info.price' tries to reorder itself towards 'product.info.review', but their parents are different: 'product.info.main' and 'product.info.price' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.price.final' tries to reorder itself towards 'product.info.sku', but their parents are different: 'product.info.price' and 'product.info.stock.sku' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.info.social' tries to reorder itself towards 'product.info.overview', but their parents are different: 'product.info.extrahint' and 'product.info.main' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'skip_gallery_before' tries to reorder itself towards 'product.info.media.image', but their parents are different: 'skip_gallery_before.wrapper' and 'product.info.media' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'skip_gallery_after' tries to reorder itself towards 'product.info.media.image', but their parents are different: 'skip_gallery_after.wrapper' and 'product.info.media' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.info.details' tries to reorder itself towards 'product.info.media', but their parents are different: 'content' and 'product.main.section' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.info.feed.sec' tries to reorder itself towards 'product.info.main', but their parents are different: 'content.top.most' and 'product.main.section' respectively. [] []
[2018-01-22 10:04:15] main.INFO: Broken reference: the 'product.info.description.accordian' tries to reorder itself towards 'product.info.extrahint', but their parents are different: 'content' and 'product.info.main' respectively. [] []

Answer 1

All of these are debug information of Magento which taken into log while processing of layout files to render html. It's very useful while you are struggling with any block is not rendering or rendering at wrong place. There will be a lot of another information as well when you proceed with other functionality of Magento 2.