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Reference – What does this error mean in PHP?

1245

What is this?

This is a number of answers about warnings, errors, and notices you might encounter while programming PHP and have no clue how to fix them. This is also a Community Wiki, so everyone is invited to participate adding to and maintaining this list.

Why is this?

Questions like “Headers already sent” or “Calling a member of a non-object” pop up frequently on Stack Overflow. The root cause of those questions is always the same. So the answers to those questions typically repeat them and then show the OP which line to change in their particular case. These answers do not add any value to the site because they only apply to the OP’s particular code. Other users having the same error cannot easily read the solution out of it because they are too localized. That is sad because once you understood the root cause, fixing the error is trivial. Hence, this list tries to explain the solution in a general way to apply.

What should I do here?

If your question has been marked as a duplicate of this one, please find your error message below and apply the fix to your code. The answers usually contain further links to investigate in case it shouldn’t be clear from the general answer alone.

If you want to contribute, please add your “favorite” error message, warning or notice, one per answer, a short description what it means (even if it is only highlighting terms to their manual page), a possible solution or debugging approach and a listing of existing Q&A that are of value. Also, feel free to improve any existing answers.

The List

Also, see:

4

199

Fatal error: Call to a member function … on a non-object

Happens with code similar to xyz->method() where xyz is not an object and therefore that method can not be called.

This is a fatal error which will stop the script (forward compatibility notice: It will become a catchable error starting with PHP 7).

Most often this is a sign that the code has missing checks for error conditions. Validate that an object is actually an object before calling its methods.

A typical example would be

// ... some code using PDO
$statement = $pdo->prepare('invalid query', ...);
$statement->execute(...);

In the example above, the query cannot be prepared and prepare() will assign false to $statement. Trying to call the execute() method will then result in the Fatal Error because false is a “non-object” because the value is a boolean.

Figure out why your function returned a boolean instead of an object. For example, check the $pdo object for the last error that occurred. Details on how to debug this will depend on how errors are handled for the particular function/object/class in question.

If even the ->prepare is failing then your $pdo database handle object didn’t get passed into the current scope. Find where it got defined. Then pass it as a parameter, store it as property, or share it via the global scope.

Another problem may be conditionally creating an object and then trying to call a method outside that conditional block. For example

if ($someCondition) {
    $myObj = new MyObj();
}
// ...
$myObj->someMethod();

By attempting to execute the method outside the conditional block, your object may not be defined.

Related Questions:

0

    124

    Nothing is seen. The page is empty and white.

    Also known as the White Page Of Death or White Screen Of Death. This happens when error reporting is turned off and a fatal error (often syntax error) occurred.

    If you have error logging enabled, you will find the concrete error message in your error log. This will usually be in a file called “php_errors.log”, either in a central location (e.g. /var/log/apache2 on many Linux environments) or in the directory of the script itself (sometimes used in a shared hosting environment).

    Sometimes it might be more straightforward to temporarily enable the display of errors. The white page will then display the error message. Take care because these errors are visible to everybody visiting the website.

    This can be easily done by adding at the top of the script the following PHP code:

    ini_set('display_errors', 1); error_reporting(~0);
    

    The code will turn on the display of errors and set reporting to the highest level.

    Since the ini_set() is executed at runtime it has no effects on parsing/syntax errors. Those errors will appear in the log. If you want to display them in the output as well (e.g. in a browser) you have to set the display_startup_errors directive to true. Do this either in the php.ini or in a .htaccess or by any other method that affects the configuration before runtime.

    You can use the same methods to set the log_errors and error_log directives to choose your own log file location.

    Looking in the log or using the display, you will get a much better error message and the line of code where your script comes to halt.

    Related questions:

    Related errors:

    4

    • 3

      error_reporting(~0); why not -1? That is what ~0 evaluates to, and is much less cryptic.

      Mar 31, 2013 at 2:43


    • 3

      I think both are similarly cryptic. ~0 is more explicit IMO: negate the empty bit set, i. e. enable all flags. -1 is not meant to stand for «not found» like in strpos() in C, but as a bitset with all flags set, because -1 is binary 1111'1111'1111'1111 (for 32 bits).

      – nalply

      Mar 31, 2013 at 12:04


    • 2

      Oops, 1111'1111'1111'1111 is really 16 bits, but I hope you understand what I mean.

      – nalply

      Mar 31, 2013 at 13:38


    • Another reason you might have got this is because you put return false; in your PHP code

      Oct 26, 2020 at 17:19