magento2: main.CRITICAL: Broken reference (Magento CE v2.1)

The following system.log entries appear in Developer Mode

@piotrekkaminski unfortunately this does not seem to be fixed in CE 2.1 per #3507 (which has been closed), so I have created a new issue.

Installation following devdocs instructions for composer and cli install. vcl for varnish 4 generated through Magento Admin. Following install ‘php bin/magento indexer:reindex’ was run.

Developer Mode File Permissions: (nginx is member of www-data group)

cd <magento_web_root_directory> && find . -type d -exec chmod 770 {} \; && find . -type f -exec chmod 660 {} \; && chown -R www-data:www-data . && chmod u+x bin/magento

Setup: Nginx (443) --> Varnish 4 --> Nginx --> Magento CE v2.1

Home: First page load after cache flush

[2016-07-13 16:43:21] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2c7461af04bb11fe209659d7147d2c579 and handles default, cms_index_index, cms_page_view, cms_index_index_id_home: Please correct the XML data and try again.  [] []
[2016-07-13 16:43:22] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_20a98983867a1770682b48d9a0ad63441 and handles 1column: Please correct the XML data and try again.  [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'paypal.partner.right.logo' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'bml.right.logo' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_26f1b068ec7ccf4878f9284dd1137afd1 and handles catalog_product_prices: Please correct the XML data and try again.  [] []
[2016-07-13 16:43:22] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2cf9ab1b1723bedc1dcd665a812b00335 and handles admin-1column: Please correct the XML data and try again.  [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'paypal.partner.right.logo' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:43:22] main.CRITICAL: Broken reference: the 'bml.right.logo' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Home: Subsequent page refresh (Ctrl + F5)

• no log entries

Privacy and Cookie Policy: First page load after cache flush

[2016-07-13 16:13:40] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2d15e9460690f60c1bc7a93d558807785 and handles default, cms_page_view, cms_page_view_id_privacy-policy-cookie-restriction-mode: Please correct the XML data and try again.  [] []
[2016-07-13 16:13:40] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:13:40] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:13:40] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:13:40] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2cf9ab1b1723bedc1dcd665a812b00335 and handles admin-1column: Please correct the XML data and try again.  [] []
[2016-07-13 16:13:40] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:13:40] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:13:40] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Privacy and Cookie Policy: Subsequent page refresh (Ctrl + F5)

• no log entries

Orders and Returns: First page load

[2016-07-13 16:17:04] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2deafad4772f91b941cf386aa0b46401e and handles default, sales_guest_form: Please correct the XML data and try again.  [] []
[2016-07-13 16:17:04] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:17:04] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:17:04] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:17:04] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:17:04] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:17:04] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Order and Returns: Subsequent page refresh (Ctrl + F5)

• no log entries

Search Terms: First page load after cache flush

[2016-07-13 16:19:37] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2dd8d68d60e557251729107544ad7e33e and handles default, search_term_popular: Please correct the XML data and try again.  [] []
[2016-07-13 16:19:37] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:19:37] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:19:37] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Search Terms: Subsequent page refreshes (Ctrl + F5)

[2016-07-13 16:24:11] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:24:11] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:24:11] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Contact Us: First page load after cache flush

[2016-07-13 16:28:29] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2c1a79df4e2fb1a01d9ef5b0d7391ab5f and handles default, contact_index_index: Please correct the XML data and try again.  [] []
[2016-07-13 16:28:29] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:28:29] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:28:29] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Contact Us: Subsequent page refreshes (Ctrl + F5)

[2016-07-13 16:29:56] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:29:56] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:29:56] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Advance Search: First page load after cache flush

• no log entries

Advanced Search: 1st page refresh (Ctrl + F5)

[2016-07-13 16:48:03] main.INFO: Cache file with merged layout: LAYOUT_frontend_STORE1_2eafd64351df05cd70fb508ddcbf7661b and handles default, catalogsearch_advanced_index: Please correct the XML data and try again.  [] []
[2016-07-13 16:48:03] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:48:03] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:48:03] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:48:03] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:48:03] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:48:03] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Advance Search: 2nd…n page refreshes (Ctrl + F5)

[2016-07-13 16:35:17] main.CRITICAL: Broken reference: the 'catalog.compare.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:35:17] main.CRITICAL: Broken reference: the 'sale.reorder.sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []
[2016-07-13 16:35:17] main.CRITICAL: Broken reference: the 'wishlist_sidebar' element cannot be added as child to 'sidebar.additional', because the latter doesn't exist [] []

Thanks