PHP session side-effect warning with global variables as a source of data

php session global-variables session-variables
Zack Peterson picture Zack Peterson · Oct 6, 2008 · Viewed 41.4k times · Source

I'm trying to host a PHP web site that was given to me. I see this warning:

Warning: Unknown: Your script possibly relies on a session side-effect which existed until PHP 4.2.3. Please be advised that the session extension does not consider global variables as a source of data, unless register_globals is enabled. You can disable this functionality and this warning by setting session.bug_compat_42 or session.bug_compat_warn to off, respectively. in Unknown on line 0

What does this mean? How might I track down the source of this problem within the code?

Answer

Owen picture Owen · Oct 6, 2008

basically you have a variable with the same name as your session. ex:

$_SESSION['var1'] = null;
$var1 = 'something';

which will reproduce this error. you can stop PHP from trying to find existing variables and warning you about them by adding these lines to your script:

ini_set('session.bug_compat_warn', 0);
ini_set('session.bug_compat_42', 0);

these values can be set in php.ini or .htaccess as well

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