Plugin activation gotcha…

UpdraftCentral version: 0.5.1
WP/4.7.3 PHP/7.0.16 MySQL/5.5.5 Curl/7.29.0
(MariaDB 10.1.21)

Installed and activated UpdraftCentral Dashboard with no visible problems. Went to add a site and got:

Error: Table 'dbname.wp_updraftcentral_sites' doesn't exist

Checked apache error logs and found:

WordPress database error Index column size too large. The maximum column size is 767 bytes. for query CREATE TABLE wp_updraftcentral_sites

Quick duckduckgo search found:
MySQL error: The maximum column size is 767 bytes
(stackoverflow, yes, I know, but it had the answer…)

So looking at updraftcentral/classes/activation.php(69) I found the table creation query. I suspect the issue is the index on the url field (based on what I see you have done with the sitemeta table below that).

So since I have the following set in my my.cnf.d includes:

innodb_file_format=Barracuda
innodb_file_per_table=1
innodb_large_prefix=1
character_set_server=utf8mb4
collation_server=utf8mb4_unicode_ci

The quick-and-dirty solution for me was to manually create the table and specify the InnoDB Row Format as DYNAMIC. Though I suspect that limiting the url index size for the sites table as you have done for the sitemeta table would probably do the trick too.

So I just manually created the table for my environment like so:

CREATE TABLE wp_updraftcentral_sites (
	site_id bigint(20) NOT NULL auto_increment,
	user_id bigint(20) NOT NULL,
	url varchar(300) NOT NULL,
	admin_url varchar(300),
	key_local_private blob,
	key_remote_public blob,
	key_name_indicator varchar(200) NOT NULL,
	description text,
	sequence_id bigint(20) DEFAULT 0,
	remote_user_id bigint(20) NOT NULL,
	remote_user_login varchar(60),
	remote_site_id bigint(20) DEFAULT 0,
	connection_method varchar(30),
	send_cors_headers tinyint(1) DEFAULT 1,
	PRIMARY KEY (site_id),
	KEY user_id (user_id),
	KEY url (url)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci ROW_FORMAT=DYNAMIC;

P.S. Sorry about back in the fall, but things are going well for me in my own ventures so far. ??