XF 1.5 1.5.4 update problems

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When entering the admin panel turns white pages and unavailable entry.

He gave the following warning before Update :

Upgrade System
The following warnings were detected when verifying that your server can run XenForo:
Your server has disabled fundamental core PHP functions via the disable_functions directive in php.ini. This will cause unexpected problems in XenForo. All PHP functions should be enabled.
These will not prevent you from using XenForo, but they should be resolved if possible to ensure optimal functioning. However, you may continue with the upgrade.
Your XenForo installation is large. If you are doing a major upgrade, you may wish to upgrade via the command line. Simply run this command and follow the on-screen instructions:
php '/home/seatclub/public_html/library/XenForo/Install/run-upgrade.php'
You can continue with the browser-based upgrade, but large queries may cause browser timeouts that will force you to reload the page.
Click the button below to begin the upgrade to 1.5.4.
Begin Upgrade
Remote connection to the MySQL server is down

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