PHP buffering error <unknown> in line 0
<p>Would anybody be kind to help me with any possible information on this error? causes? login? where to look/start?</p>

<pre><code> Cannot use output buffering in output buffering display handlers in &lt;**Unknown**&gt; on line **0**
</code></pre>

<p>Example code:</p>

<pre><code>function test($b) { return _strrev($b); } 

ob_start("test"); 
echo "123"; 
ob_end_flush();
</code></pre>

<p>Information:</p>

<ul>
<li>This is CentOS 6.7</li>
<li>This is PHP PHP 5.5.32 (cli)</li>
<li>This is NOT Wordpress</li>
<li>This is a simple PHP file with pseudo code (above)</li>
<li>No caching, no Varnish, no Nginx, no custom headers</li>
</ul>

<p>Thanks</p>