Modified PHP settings caused errors on my Joomla 3.x site

[webgyrl]

I am going through trying to harden security on all my Joomla sites.

I have been experimenting with PHP settings and turned these off using a php.ini file in the main folder of this site on my shared hosting server (SiteGround).

expose_php = Off
register_globals = Off
register_long_arrays = Off
register_argc_argv = Off
magic_quotes_gpc = Off
magic_quotes_runtime = Off
magic_quotes_sybase = Off

I just tried it and got this error:

Warning: array_key_exists() expects parameter 2 to be array, null given in /home/xxxxx/public_html/domain.com/libraries/cms.php on line 62
Error displaying the error page: Application Instantiation Error: Failed to start the session because headers have already been sent by "/home/xxxxx/public_html/domain.com/libraries/cms.php" at line 62.

Server is shared server, but I uploaded php.ini to the specific website folder. Settings are:
PHP Built On Linux 3.12.18-clouder0 #85 SMP Mon Apr 3 10:28:14 EEST 2017 x86_64
Database Version 5.6.36-82.1-log
Database Collation utf8_general_ci
Database Connection Collation utf8mb4_general_ci
PHP Version 7.0.25
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 3.8.2 Stable [ Amani ] 7-November-2017 15:00 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT

Any ideas why the site failed?

Thanks!

[itoctopus]

Your $_SERVER PHP array is passed empty. Not sure which of the above settings caused it. I would experiment by enabling them one by one until the culprit is found.

[webgyrl]

Ok thanks I will try that. Cheers!

[JAVesey]

Warning: array_key_exists() expects parameter 2 to be array, null given in /home/xxxxx/public_html/domain.com/libraries/cms.php on line 62
Error displaying the error page: Application Instantiation Error: Failed to start the session because headers have already been sent by "/home/xxxxx/public_html/domain.com/libraries/cms.php" at line 62.

...

Any ideas why the site failed?

Yes! Same thing happened to me after I moved servers and updated the PHP version.

Solution:
In /administrator:

System > Clear Caches

Clear the site cache and the expired cache.

[webgyrl]

Thanks! I got it fixed.

[JAVesey]

Thanks! I got it fixed.

It would help others if you shared the solution.

[webgyrl]

Thanks! I got it fixed.

It would help others if you shared the solution.

It was with the clear cache suggestion above my latest post.

[JAVesey]

It was with the clear cache suggestion above my latest post.