Please enable error logging on ACP >> Home » Board Settings » Server and Optimization Options and install the plugin again.
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attachment=45548]
I'm getting :
SQL Error:
1364 - Field 'default_tab' doesn't have a default value
Which tab plugin are you using?
You can try running this query in PHPMyAdmin
ALTER TABLE mybb_users MODIFY default_tab int NOT NULL DEFAULT '0'
As referenced
here though I've modified it to use the issue you're having with default_tab.
OR
You can deactivate AND uninstall the plugin and alter the file (probably a better route to go).
After uninstall go to the file (inc > plugins > mytabs.php) and find line 115:
$db->add_column('users', 'default_tab', 'TEXT NOT NULL DEFAULT 0');
Change it to this:
$db->add_column("users", "default_tab", "TEXT NOT NULL DEFAULT '0'");
Save and then go back to your Admin CP and reinstall/activate the plugin.
Depending on the mysql/mariadb version, TEXT column cannot have a default value