HTTP ERROR 500 can't access admin

[Gidget_NC]

The site is working fine, but when I go to the admin I get an HTTP ERROR 500 message. My hosting company said the following errors are the cause -

25-Oct-2019 01:13:12 UTC] PHP Fatal error: Call to undefined method JAdministrator::setHeader() in /home/site/public_html/libraries/cms/html/behavior.php on line 778
[25-Oct-2019 01:13:18 UTC] PHP Strict Standards: Only variables should be assigned by reference in /home/site/public_html/plugins/system/jsecure/jsecure.php on line 19
[25-Oct-2019 01:13:18 UTC] PHP Strict Standards: Non-static method JPlugin::loadLanguage() should not be called statically in /home/site/public_html/plugins/system/jsecure/jsecure.php on line 23
[25-Oct-2019 01:13:18 UTC] PHP Strict Standards: Only variables should be assigned by reference in /home/site/public_html/plugins/system/jsecure/jsecure.php on line 40
[25-Oct-2019 01:13:18 UTC] PHP Strict Standards: Only variables should be assigned by reference in /home/site/public_html/plugins/system/jsecure/jsecure.php on line 48
[25-Oct-2019 01:13:18 UTC] PHP Strict Standards: Only variables should be assigned by reference in /home/site/public_html/plugins/system/jsecure/jsecure.php on line 58
[25-Oct-2019 01:13:18 UTC] PHP Fatal error: Call to undefined method JAdministrator::setHeader() in /home/site/public_html/libraries/cms/html/behavior.php on line 778

Please advise how I can fix this. Thank you!

[toivo]

Did your host happen to upgrade PHP to version 7 before the errors started appearing?

It looks like the website has an old version of jSecure that does not support PHP 7. More than likely you have to ask your host to downgrade PHP until you have an upgrade plan for the Joomla 2.5 site and its third party extensions.

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