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utf 8 - php mb_convert_variables RECURSION error

I am developing a website using PHP and I am encountering an error related to using the mb_convert_variables function with UTF-8 encoding. When I try to use this function, I receive a "RECURSION" error. Here is the code snippet that is causing the issue:

$input = "Hello World";
$output = mb_convert_variables('UTF-8', 'UTF-8', $input);

I am not sure why this error is occurring and I couldn't find much information online about it. Can someone please help me understand the cause of this error and how to resolve it? Thank you in advance.

All Replies


Hmm, I haven't encountered the exact "RECURSION" error with mb_convert_variables function, but I did face a similar issue with another function in PHP. In my case, the recursion error occurred due to an infinite loop caused by a circular reference within the input data.

To troubleshoot this issue, I suggest checking if your input data contains any circular references. Circular references can occur if you have nested arrays or objects that reference each other in a loop-like manner.

One way to identify circular references is by using the PHP built-in function `json_encode` with the `JSON_THROW_ON_ERROR` flag. Try encoding your input data like this:

$input = "Hello World";
try {
$json = json_encode($input, JSON_THROW_ON_ERROR);
} catch (JsonException $e) {
echo $e->getMessage();

If the `json_encode` call throws a "Maximum stack depth exceeded" error, it indicates the presence of circular references. In that case, you will need to manually inspect and break the circular reference in your data structure before passing it to the `mb_convert_variables` function.

Once you identify and resolve any circular references, you can then use the updated code provided by User 1 to convert the variables to UTF-8. Hopefully, this helps you diagnose and resolve the "RECURSION" error you are encountering. Let me know if you need further assistance!


I have encountered a similar issue with the mb_convert_variables function in the past. In my case, the recursion error was caused due to an infinite loop in the script. This can happen if the input variable being passed to the function is already in UTF-8 encoding.

To fix the error, you can add a simple check to ensure that the input variable is not already in UTF-8. Here's an updated version of your code:

$input = "Hello World";

// Check the current encoding of the input variable
$currentEncoding = mb_detect_encoding($input, 'UTF-8', true);

// Only convert if the input variable is not already in UTF-8
if ($currentEncoding !== 'UTF-8') {
$output = mb_convert_variables('UTF-8', $currentEncoding, $input);
} else {
$output = $input;

echo $output;

By using the `mb_detect_encoding` function, we can determine the current encoding of the input variable. If it is already in UTF-8, we can directly assign it to the output variable. Otherwise, we perform the `mb_convert_variables` function to convert it to UTF-8.

Give this code a try and see if it resolves the "RECURSION" error for you. Let me know if you have any further queries!

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