I get invalid header errors after upgrading to 2011.6.

I tracked the issue down to operator precedence in php.

When a string and ternary operator are concatenated you need to surround the ternary of you get the boolean value concatenated.

The issue is in /lib/ezfile/classes/ezfile.php

line 253 has

header(
"Content-Disposition: " .
( $isAttachedDownload ? 'attachment' : 'inline' ) .
( $overrideFilename !== false ) ? "; filename={$overrideFilename}" : ''
);

should have

header(
"Content-Disposition: " .
( $isAttachedDownload ? 'attachment' : 'inline' ) .
(( $overrideFilename !== false ) ? "; filename={$overrideFilename}" : '')
);