Originally reported on Russian IST board: http://www.phpbbguru.net/community/topic16064-420.html#p326091
- output_buffering is set to 4096 in php.ini;
- gzip compression is enabled in phpbb;
- a warning or a notice is produced somewhere,
then the resulting output is not a valid compressed stream, although it has gzip headers, and results in different browsers either reporting a compression error or just displaying nothing.
In includes/functions.php line #3746 (current develop-olympus) there's a check:
As per PHP manual on output_buffering setting:
You can enable output buffering for all files by setting this directive to 'On'. If you wish to limit the size of the buffer to a certain size - you can use a maximum number of bytes instead of 'On', as a value for this directive (e.g., output_buffering=4096). As of PHP 4.3.5, this directive is always Off in PHP-CLI.
Thus, the value of output_buffering setting in switched on state can differ from 1 or on.
This causes page can't be displayed on E_NOTICE or E_WARNING in some cases.