I found that the error log grew huge. Every time I open media library the following message (or something like it) gets added to the error log:
[25-Jan-2017 21:07:06 UTC] WordPress database error Specified key was too long; max key length is 1000 bytes for query CREATE TABLE IF NOT EXISTS mcnv_zara4_file_compression_metadata (
file-path varchar(512) NOT NULL,
request-id varchar(255) NOT NULL,
is-compressed BOOLEAN NOT NULL DEFAULT FALSE,
original-file-size BIGINT UNSIGNED NULL DEFAULT NULL,
compressed-file-size BIGINT UNSIGNED NULL DEFAULT NULL,
original-file-hash varchar(50) NULL DEFAULT NULL,
compressed-file-hash varchar(50) NULL DEFAULT NULL,
bytes-saved INT UNSIGNED NULL DEFAULT NULL,
percentage-saving DECIMAL(10,7) NULL DEFAULT NULL,
no-saving-available BOOLEAN NOT NULL DEFAULT FALSE,
plugin-version varchar(10) NOT NULL,
PRIMARY KEY (file-path)
) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci made by require_once(‘wp-load.php’), require_once(‘wp-config.php’), require_once(‘wp-settings.php’), do_action(‘plugins_loaded’), WP_Hook->do_action, WP_Hook->apply_filters, call_user_func_array, Zara4_WordPress_Install_Installer::install, Zara4_WordPress_Install_Database::create_file_compression_metadata_table, dbDelta
[25-Jan-2017 21:07:06 UTC] WordPress database error Invalid default value for ‘created-at’ for query CREATE TABLE IF NOT EXISTS mcnv_zara4_exclude_from_bulk_compression (
file-path varchar(512) NOT NULL,
created-at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (file-path)
) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci made by require_once(‘wp-load.php’), require_once(‘wp-config.php’), require_once(‘wp-settings.php’), do_action(‘plugins_loaded’), WP_Hook->do_action, WP_Hook->apply_filters, call_user_func_array, Zara4_WordPress_Install_Installer::install, Zara4_WordPress_Install_Database::create_exclude_from_bulk_compression_table, dbDelta
