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session - Undefined variable: _SESSION php login script

Hey everyone,

So I'm currently working on a PHP login script, but I seem to be encountering an issue with an undefined variable: _SESSION. I'm not exactly sure what it means or how to fix it.

Here's some context about my script: I have a login form where users can enter their username and password. The form submits to a PHP script that checks if the credentials are valid, and if so, it sets some session variables to store information about the logged-in user.

However, when I try to access these session variables later on in my script or on another page, I get an error saying "Undefined variable: _SESSION". I'm not sure why this is happening or what I need to do to resolve it.

I've made sure that I have the session_start() function at the top of my PHP files, so I don't think that's the problem. I've also checked my php.ini file to ensure that the session module is enabled, and it seems to be fine there as well.

I'm wondering if I'm missing something in my code or if there's some configuration I need to set up to make sessions work correctly. Any guidance or suggestions would be greatly appreciated.

Thanks in advance!

All Replies


Hey everyone,

I've also encountered the "Undefined variable: _SESSION" error while working on a PHP login script, and I'd like to share my experience in resolving it. In my case, the issue was due to an incorrect configuration of the session.save_path in my php.ini file. Double-checking this configuration and ensuring the correct directory and permissions were set fixed the problem for me.

Additionally, I learned that the error might occur if the session variables are not being properly set after the login process. So, it's important to carefully review your code and make sure you are assigning values to the $_SESSION variables once the user credentials are validated.

Another factor that could cause this error is if the session variables are not being carried over between different PHP scripts or pages. In such cases, make sure you have correctly included the session_start() function at the beginning of every PHP file where you want to access the $_SESSION variables.

Lastly, if you're working on a shared hosting environment, it's worth noting that sometimes the server's session configuration can interfere with your script. In such cases, contacting your hosting provider's support team to check if there are any specific restrictions or configurations that could lead to this error might be helpful.

I hope these insights help you find a solution to your problem. Feel free to reach out if you have any further questions or need more clarification.

Best regards,
User 2


Hey there,

I've faced a similar issue before with the "Undefined variable: _SESSION" error in my PHP login script. In my case, the problem stemmed from not having the session_start() function placed at the very beginning of my PHP files. So, I would recommend double-checking if you have that function correctly located at the top of all relevant PHP pages.

Another thing to watch out for is any syntax errors or typos in your code. It's crucial to ensure that you have correctly spelled the variable name as $_SESSION. Remember, PHP is case-sensitive, so using _SESSION instead of $_SESSION can cause the error you're encountering.

If you've ensured that the session_start() function is present and the variable name is correct, you might also want to examine your PHP configuration settings. Check if the PHP sessions module is enabled and that the session.save_path is properly defined in your php.ini file.

Lastly, it's worth mentioning that you should avoid any output or echo statements before the session_start() function, as they can prevent session variables from being properly established.

I hope these tips help you troubleshoot your issue. Let me know if you need any further assistance!

Best regards,
User 1

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