Hi Support,
I’m getting an error upon installing that causes all pages to give a 500 error.
This site is hosted on wordpress.com and therefor I have limited access to the backend.

Any ideas what can be done to resolve?

1.
15125762570.76192200 E_NOTICE: /wordpress/drop-ins/object-cache.php:193 - Undefined index: delete
require('wp-blog-header.php'), require_once('wp-load.php'), require_once('/wpcom-122520772/wp-config.php'), require_once('wp-settings.php'), do_action('wp_loaded'), WP_Hook->do_action, WP_Hook->apply_filters, WP_Rewrite->flush_rules, update_option, do_action('updated_option'), WP_Hook->do_action, WP_Hook->apply_filters, Pressable_Mu_Plugin->maybe_clear_alloptions_cache, wp_cache_delete, WP_Object_Cache->delete

2.
15125762580.21897000 E_NOTICE: /wpcom-122520772/wp-content/plugins/um-switcher/um-switcher.php:1374 - Only variables should be passed by reference
require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/Avada/100-width.php'), get_footer, locate_template, load_template, require_once('/themes/Avada/footer.php'), wp_footer, do_action('wp_footer'), WP_Hook->do_action, WP_Hook->apply_filters, umswitcher_profile_subscription_expiration_footer, umswitcher_profile_subscription_expiration

3.
WordPress database error Duplicate column name 'UmWoTD_subscription_type' for query ALTER TABLE wp_1225207**_um_switcher ADD COLUMN 
UmWoTD_subscription_type int(1) NOT NULL made by include('phar:///usr/local/bin/wp-cli/php/boot-phar.php'), include('phar:///usr/local/bin/wp-cli/php/wp-cli.php'), WP_CLI\bootstrap, WP_CLI\Bootstrap\LaunchRunner->process, WP_CLI\Runner->start, WP_CLI\Runner->load_wordpress, require('/opt/sites/10409**/wordpress/core/4.9.1/wp-settings.php'), include_once('/plugins/um-switcher/um-switcher.php'), Um_Switcher->construct
WordPress database error Duplicate column name 'subscription_type_start_date' for query ALTER TABLE wp_1225207**_um_switcher ADD COLUMN 
subscription_type_start_date date NOT NULL made by include('phar:///usr/local/bin/wp-cli/php/boot-phar.php'), include('phar:///usr/local/bin/wp-cli/php/wp-cli.php'), WP_CLI\bootstrap, WP_CLI\Bootstrap\LaunchRunner->process, WP_CLI\Runner->start, WP_CLI\Runner->load_wordpress, require('/opt/sites/1040**/wordpress/core/4.9.1/wp-settings.php'), include_once('/plugins/um-switcher/um-switcher.php'), Um_Switcher->construct
WordPress database error Duplicate column name 'subscription_type_end_date' for query ALTER TABLE wp_1225207**_um_switcher ADD COLUMN 
subscription_type_end_date date NOT NULL made by include('phar:///usr/local/bin/wp-cli/php/boot-phar.php'), include('phar:///usr/local/bin/wp-cli/php/wp-cli.php'), WP_CLI\bootstrap, WP_CLI\Bootstrap\LaunchRunner->process, WP_CLI\Runner->start, WP_CLI\Runner->load_wordpress, require('/opt/sites/10409**/wordpress/core/4.9.1/wp-settings.php'), include_once('/plugins/um-switcher/um-switcher.php'), Um_Switcher->__construct
PHP Warning: file_put_contents(/opt/sites/10409**/wordpress/core/4.9.1/dbversion): failed to open stream: Permission denied in /opt/sites/10409**/wpcom-122520772/wp-content/plugins/um-switcher/um-switcher.php on line 164
Warning: file_put_contents(/opt/sites/10409**/wordpress/core/4.9.1/dbversion): failed to open stream: Permission denied in /opt/sites/10409**/wpcom-1225207**/wp-content/plugins/um-switcher/um-switcher.php on line 164
PHP Warning: file_put_contents(/opt/sites/10409**/wordpress/core/4.9.1/dbversion): failed to open stream: Permission denied in /opt/sites/10409**/wpcom-1225207**/wp-content/plugins/um-switcher/um-switcher.php on line 165
Warning: file_put_contents(/opt/sites/10409**/wordpress/core/4.9.1/dbversion): failed to open stream: Permission denied in /opt/sites/10409**/wpcom-1225207**/wp-content/plugins/um-switcher/um-switcher.php on line 165