New Error Log Entries

Hello,

We are running a WP 4.6.1 multiste network with your plugin active on several subsites.

Can you advise what these errors in our logs indicate?
This is the first time we have encountered them.

[04-Oct-2016 16:31:11 UTC] WordPress database error Not unique table/alias: ‘wp_81_postmeta’ for query SELECT DISTINCT wp_81_posts.* FROM wp_81_posts INNER JOIN wp_81_postmeta ON ( wp_81_posts.ID = wp_81_postmeta.post_id ) INNER JOIN wp_81_postmeta AS mt1 ON ( wp_81_posts.ID = mt1.post_id ) LEFT JOIN wp_81_postmeta ON wp_81_posts.ID = wp_81_postmeta.post_id LEFT JOIN wp_81_term_relationships AS trel ON (wp_81_posts.ID = trel.object_id) LEFT JOIN wp_81_term_taxonomy AS ttax ON ( ( ttax.taxonomy = ‘category’ OR ttax.taxonomy = ‘post_tag’ OR ttax.taxonomy = ‘post_format’ OR ttax.taxonomy = ‘avhec_catgroup’ OR ttax.taxonomy = ‘cn_log_type’ OR ttax.taxonomy = ‘wpm-testimonial-category’ OR ttax.taxonomy = ‘campaign_category’ OR ttax.taxonomy = ‘campaign_tag’ OR ttax.taxonomy = ‘filter_group’ OR ttax.taxonomy = ‘bcat’ OR ttax.taxonomy = ‘advanced_faq_category’ OR ttax.taxonomy = ‘advanced_faq_topics’ OR ttax.taxonomy = ‘staff_tag’ OR ttax.taxonomy = ‘staff_category’ OR ttax.taxonomy = ‘post_status’ OR ttax.taxonomy = ‘ef_editorial_meta’ OR ttax.taxonomy = ‘following_users’ OR ttax.taxonomy = ‘ef_usergroup’ OR ttax.taxonomy = ‘pdf_lv_category’ OR ttax.taxonomy = ‘pdf_lv_tag’ ) AND trel.term_taxonomy_id = ttax.term_taxonomy_id) LEFT JOIN wp_81_terms AS tter ON (ttax.term_id = tter.term_id) WHERE 1=1 AND ( ( (
( wp_81_postmeta.meta_key = ‘_pdf-light-viewer-import-progress’ AND CAST(wp_81_postmeta.meta_value AS SIGNED) < ‘100’ )
AND
( mt1.meta_key = ‘_pdf-light-viewer-import-status’ AND mt1.meta_value != ‘failed’ )
AND
( mt1.meta_key = ‘_pdf-light-viewer-import-status’ AND mt1.meta_value != ‘cli_processing’ )
AND
( mt1.meta_key = ‘_pdf-light-viewer-import-status’ AND mt1.meta_value != ‘finished’ )
) AND wp_81_posts.post_type = ‘pdf_lv’ AND (wp_81_posts.post_status = ‘publish’ OR wp_81_posts.post_status = ‘future’ OR wp_81_posts.post_status = ‘idea’ OR wp_81_posts.post_status = ‘pitch’ OR wp_81_posts.post_status = ‘assigned’ OR wp_81_posts.post_status = ‘in-progress’ OR wp_81_posts.post_status = ‘draft’ OR wp_81_posts.post_status = ‘draft-needs-image’ OR wp_81_posts.post_status = ‘pending-review’ OR wp_81_posts.post_status = ‘private’)) AND post_type != ‘revision’) AND post_status != ‘future’ GROUP BY wp_81_posts.ID ORDER BY wp_81_posts.post_date DESC made by require_once(‘wp-admin/admin-header.php’), do_action(‘admin_enqueue_scripts’), PdfLightViewer_AssetsController::admin_head, PdfLightViewer_Model::getOneUnimported, WP_Query->__construct, WP_Query->query, WP_Query->get_posts, QM_DB->query
[04-Oct-2016 16:36:08 UTC] PHP Warning: Invalid argument supplied for foreach() in /home/soobabiz/public_html/wp-admin/includes/plugin.php on line 1422

Any insights will be appreciated.

Thanks