 <p><code>NBSP</code>. You had an invisible non-standard whitespace character before your require statement. That's the only reliable way to reproduce this error.</p> <pre><code>eval( chr(0xA0) . ' require_once(1); ' ); # that's nbsp // PHP Parse error: syntax error, unexpected T_REQUIRE_ONCE in </code></pre> <p><code>0xA0</code>/nbsp gets interpreted as bareword at that position. Basically the same as having a constant right in front of your statement:</p> <pre><code>ASCII require_once(123); </code></pre>