Cannot use output buffering in output buffering display handlers

Question

I've reinstalled Apache, and switched from PHP 5.3 to 5.6. Everything works, except I get this error, when calling ob_start():

Cannot use output buffering in output buffering display handlers

I tried to enable output buffering in PHP, but I still get this error:

output_buffering = 4096

Whats the memory limit in the used php.ini, i think if you set it to a higher value it will work. — Wolfeh, Nov 26 '15 at 10:34
Can you provide us with a little more information of where and how you are using the ob_start? — Wolfeh, Nov 26 '15 at 11:14
We replace every `{{TEXTID}}` string in the output to the appropriate text — Iter Ator, Nov 26 '15 at 11:18
can you add that bit of code to the question so we can see it? like Alex said do you output the buffer in the callback, or are you actually using a callback for the ob_start — Wolfeh, Nov 26 '15 at 11:27
please copy all the code thats causing the error, now we're missing a lot of information that we can use to fix the error, replace sensitive data with ******, there's no context for us to work with. you're saying ob_start causes the bug, but i can tell you that's not the problem, it's the callback function that has the error. — Wolfeh, Nov 26 '15 at 14:41
maybe interesting? [ob_get_status — Get status of output buffers](http://php.net/manual/en/function.ob-get-status.php) — Ryan Vincent, Dec 02 '15 at 13:16

Antony Thompson · Answer 1 · 2016-05-25T22:25:58.173

You're trying to start a output buffer inside a buffer callback. If you use this code, it will generate that error. But if you remove the ob_start() from the callback function it's OK.

<?php
error_reporting(-1);

function callback($buffer){
    //you can't call ob_start here
    ob_start();
    return (str_replace("apples", "oranges", $buffer));
}

ob_start("callback");

?>
<html>
<body>
<p>It's like comparing apples to oranges.</p>
</body>
</html>
<?php
ob_end_flush();

score 4 · Answer 2 · answered Mar 13 '22 at 22:08

Even though this is an old question, I just wanted to add that the same error occurs when the system runs out of memory while buffering.

If this is the case, the error mentioned in this topic will always be followed by an Allowed memory size of xxx bytes exhausted error.

score 2 · Accepted Answer · answered Dec 08 '15 at 00:19

Probably you are using a buffering function in output buffering callback which isn't possible as mentioned in php ob_start output_callback documentation. If not it should be the output-handler you used, check your php.ini and try to set it's value to "none" if possible.

score 0 · Answer 4 · answered Dec 08 '15 at 15:50

0

maybe this sample code can help you:

ob_start();
echo "test";
$content = ob_get_contents();
ob_end_clean();
var_dump($content);

answered Dec 08 '15 at 15:50

mmta41

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Cannot use output buffering in output buffering display handlers

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