How can I avoid PHP session errors?

Question

Occassionaly I run accross this error in PHP, how can I fix this or what cause it?

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

thats a tough one my site is compile of hundreds of pages but generally my header file is first and this error usually only shows up on some pages after I post something with a form then redirect to a page — JasonDavis
– JasonDavis, Commented Aug 7, 2009 at 19:07
I fixed it, some pages show a session message sitewide when I need to show a user a custom message, it then shows the session value then unsets the session, the problem was I was unsetting the session by assigning it a blank value, now I use unset($_SESSION['sess_msg']); and the error is gone — JasonDavis
– JasonDavis, Commented Aug 7, 2009 at 19:33

stereoscott · Accepted Answer · 2009-08-07 19:09:49Z

6

If your variable names are the same as the session parameters then this version of PHP will incorrectly recognize this as the programmer incorrectly relying on register_globals for session variables. Rename your variables and the warning should go away.

$mySessionVar = $_session["sessionVar"];

and not

$sessionVar = $_session["sessionVar"];

answered Aug 7, 2009 at 19:09

stereoscott

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zombat Over a year ago

Interesting. I never checked out session.bug_compat_42 before. +1 for you and Gumbo.

zombat · Accepted Answer · 2009-08-07 19:22:24Z

2

You are relying on a deprecated feature of PHP, called register_globals. This feature caused many security issues, and shouldn't be used any longer. The PHP manual discusses this in-depth.

For an excellent description of the problem, see this Google Groups post.

Edit: If you aren't relying on register_globals, then you should pay attention to Gumbo and stereointeractive's answers.

edited Aug 7, 2009 at 19:22

answered Aug 7, 2009 at 19:07

zombat

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Comments

Gumbo · Accepted Answer · 2009-08-07 19:06:18Z

1

Just disable session.bug_compat_42 and session.bug_compat_warn as the error message suggests.

answered Aug 7, 2009 at 19:06

Gumbo

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2 Comments

Otterfan Over a year ago

Error messages exist for a reason and shouldn't be disabled during developemtn. At least make sure you understand why you're getting an error message before you disable it.

Otterfan Over a year ago

OK, now that I read stereoactive's advice I see why you might disable in this one case.

acrosman · Accepted Answer · 2009-08-07 19:13:35Z

0

I would NOT suggest you disable the warnings or error messages, this is a problem you probably want to fix. Either you have variables names that are triggering bogus error message (see sterrointerative.com's answer) or you're trying to use global variables without defining them (which means you likely have bugs you can't see). In my opinion that's an important difference you want to sort out.

If it's only happening on some pages, you're likely going to have to review all the code pulled into those pages and search for use of variables that don't appear to be defined before they are used. Stepping through those pages with a debugger ought to help.

answered Aug 7, 2009 at 19:13

acrosman

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JasonDavis Over a year ago

I store messages like error messages into a session variable, on a page load if this session is not null I display it, then I unset the session variable right after showing it, I notice this error only happens sometimes but everytime it does happen it is right after one of my messages is shown and then it will not unset it on that page either when this error occurs

danamlund · Accepted Answer · 2009-08-07 19:05:41Z

-5

error_reporting(0) disables all error messages.

answered Aug 7, 2009 at 19:05

danamlund

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zombat Over a year ago

This is not a good solution. It will only hide issues with your code, and lead to future problems.

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