my_calendar_category_relationships table doesn’t exist?

That should have been created as part of the upgrade process, yes – the upgrade db process runs during every update.

All you should need to do to trigger it again is deactivate and reactivate the plug-in, so try that first.

Deleting the plug-in won’t lose your data, as long as your settings are correct, but you *will* lose all your plug-in settings, so if you can avoid deleting, that’s probably easier.

I am also having this issue on a multisite installation. I have deactivated and reactivated and also deleted and reinstalled with no success.
Some of the sites seem to be present, but it continually creates items in the error log such as
The “My Calendar” plugin is looking in the table Obz9_23_my_calendar_category_relationships but not finding it. (where 23 relates to the sub site)
Other subsite numbers exist
Whats do you suggest?

Do you have any error log items specific to attempting to create the table? A record of what error prevented the table from being created would be helpful in assessing the problem.

Yes, see below a sample

SELECT *, UNIX_TIMESTAMP(occur_begin) AS ts_occur_begin, UNIX_TIMESTAMP(occur_end) AS ts_occur_end
FROM obz9_20_my_calendar_events
JOIN obz9_20_my_calendar AS e
ON (event_id=occur_event_id)
JOIN obz9_20_my_calendar_categories AS c
ON (event_category=category_id)
JOIN obz9_20_my_calendar_category_relationships AS r ON r.event_id = e.event_id
WHERE event_flagged <> 1 AND event_approved = 1 AND r.category_id IN (1)
AND ( DATE(occur_begin) BETWEEN ‘2021-05-01 00:00:00’ AND ‘2021-06-30 23:59:59’
OR DATE(occur_end) BETWEEN ‘2021-05-01 00:00:00’ AND ‘2021-06-30 23:59:59’
OR ( DATE(‘2021-05-01’) BETWEEN DATE(occur_begin) AND DATE(occur_end) )
OR ( DATE(‘2021-06-30’) BETWEEN DATE(occur_begin) AND DATE(occur_end) ) )

ORDER BY occur_begin, event_title ASC made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, my_calendar_print_view, my_calendar_print, my_calendar, my_calendar_events, my_calendar_get_events
[28-Jun-2019 21:50:40 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_19_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_19_my_calendar_category_relationships as r JOIN obz9_19_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 31 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 21:50:40 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_19_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_19_my_calendar_category_relationships as r JOIN obz9_19_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 27 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 82 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 83 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 84 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 86 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 85 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 87 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 88 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:05:47 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_18_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_18_my_calendar_category_relationships as r JOIN obz9_18_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 89 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/front-page.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:09:03 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 23 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, mc_hidden_event, mc_get_event, mc_event_object, mc_get_categories
[28-Jun-2019 22:09:03 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 23 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/page.php’), do_action(‘kadence_page_content’), WP_Hook->do_action, WP_Hook->apply_filters, ascend_page_content, get_template_part, locate_template, load_template, require(‘/themes/ascend_premium/templates/content-page.php’), the_content, apply_filters(‘the_content’), WP_Hook->apply_filters, do_shortcode, preg_replace_callback, do_shortcode_tag, my_calendar_insert, my_calendar, mc_get_event, my_calendar_draw_event, mc_create_tags, mc_get_categories
[28-Jun-2019 22:09:03 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 23 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/page.php’), do_action(‘kadence_page_content’), WP_Hook->do_action, WP_Hook->apply_filters, ascend_page_content, get_template_part, locate_template, load_template, require(‘/themes/ascend_premium/templates/content-page.php’), the_content, apply_filters(‘the_content’), WP_Hook->apply_filters, do_shortcode, preg_replace_callback, do_shortcode_tag, my_calendar_insert, my_calendar, mc_get_event, my_calendar_draw_event, mc_create_tags, mc_get_categories
[28-Jun-2019 22:09:03 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 23 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/page.php’), do_action(‘kadence_page_content’), WP_Hook->do_action, WP_Hook->apply_filters, ascend_page_content, get_template_part, locate_template, load_template, require(‘/themes/ascend_premium/templates/content-page.php’), the_content, apply_filters(‘the_content’), WP_Hook->apply_filters, do_shortcode, preg_replace_callback, do_shortcode_tag, my_calendar_insert, my_calendar, mc_get_event, my_calendar_draw_event, mc_event_classes, mc_get_categories
[28-Jun-2019 22:12:10 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 33 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/single.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:12:10 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 39 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/single.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories
[28-Jun-2019 22:12:10 UTC] WordPress database error Table ‘domainorg_h01t1.obz9_20_my_calendar_category_relationships’ doesn’t exist for query SELECT * FROM obz9_20_my_calendar_category_relationships as r JOIN obz9_20_my_calendar_categories as c ON c.category_id = r.category_id WHERE event_id = 40 made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/ascend_premium/single.php’), get_sidebar, locate_template, load_template, require_once(‘/themes/ascend_premium/sidebar.php’), dynamic_sidebar, WP_Widget->display_callback, My_Calendar_Upcoming_Widget->widget, my_calendar_upcoming_events, mc_get_all_events, mc_get_categories

That’s not an error related to table creation – it’s an instance of attempting to use the table; do you have any errors that are specifically about *creating* the table?