Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 78

Warning: ob_start(): output handler 'ob_gzhandler'
cannot be used after 'URL-Rewriter' in file
/include/cp_functions.php line 33

Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 78
Notice: Only variables should be assigned by reference
in file /class/xoopslists.php line 200
Notice: Only variables should be assigned by reference
in file /kernel/module.php line 542
Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 155
Notice: Only variables should be assigned by reference
in file /kernel/tplset.php line 193
Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 136
Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 94
Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 94
Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 94
Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 174
Warning: ob_start(): output handler 'ob_gzhandler'
cannot be used after 'URL-Rewriter' in file
/include/cp_functions.php line 33

Notice: Only variables should be assigned by reference
in file /modules/system/admin/preferences/main.php line 50
Warning: ob_start(): output handler 'ob_gzhandler'
cannot be used after 'URL-Rewriter' in file
/include/cp_functions.php line 33

Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 78
Notice: Only variables should be assigned by reference in file /class/xoopslists.php line 200
Notice: Only variables should be assigned by reference in file /kernel/module.php line 542
Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 155
Notice: Only variables should be assigned by reference in file /kernel/tplset.php line 193
Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 136
Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 94
Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 94
Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 94
Notice: Only variables should be assigned by reference in file /modules/system/admin/preferences/main.php line 174
Warning: ob_start(): output handler 'ob_gzhandler' cannot be used after 'URL-Rewriter' in file /include/cp_functions.php line 33

Notice: Undefined variable: conf_ids in file /modules/system/admin/preferences/main.php line 338

$xoopsConfigUser =& $config_handler->getConfigsByCat(XOOPS_CONF_USER);

if (empty($xoopsConfigUser['allow_register'])) {
redirect_header('index.php', 6, _US_NOREGISTER);
exit();
}

if (empty($xoopsConfigUser['allow_register'])) {
//redirect_header('index.php', 6, _US_NOREGISTER);
//exit();
}

McDonald wrote:
Where do you see errors?
I see notices only.
Notices are not errors, and if you switch off the PHP debugger they're gone.

Please use the search option in the right top corner and use the powers of this forum.
These 2 will lead you to all your answers.
Also check out the XOOPS FAQ.

Warning: ob_start(): output handler 'ob_gzhandler'
cannot be used after 'URL-Rewriter' in file
/include/cp_functions.php line 33

erm... you are right.
I disable the gzip, and now are fixed.. strange.. i am using the 2.0.14 with no hack.. and with 2.2.4 dont show nothing notices, warnings.