Cannot manipulate headers - already sent

[Cyril Shtumf]

Hi! Work with the sessions always returns an error "Cannot manipulate 
headers - already sent". Please help! My Apache config looks like this:

<VirtualHost *:8080>
        ServerAdmin ad...@somesite.com
        ServerAlias *.somesite.com
        ServerName  somesite.com
        UseCanonicalName On

        CustomLog 
/home/webserver/somesite/www/logs/access_log.apache.log combined
        ErrorLog /home/webserver/somesite/www/logs/errors_log.apache.log
        TransferLog 
/home/webserver/somesite/www/logs/transfers_log.apache.log

        DocumentRoot /home/webserver/somesite/www/html/

        RivetServerConf ChildInitScript "package require DIO; 
::DIO::handle Mysql db -user xxx -host localhost -db xxx -pass xxx"

        RivetServerConf ChildInitScript "package require Session; 
Session SESSION -entropyFile /dev/random -entropyLength 10 -debugMode 1 
-dioObject db -sessionTable session"

<Directory "/home/webserver/somesite/www/html/">
                RivetDirConf BeforeScript "SESSION activate"
                AllowOverride All
                Options +FollowSymLinks +ExecCGI
                Order allow,deny
                Allow from all
                DirectoryIndex index.html index.htm index.rvt
</Directory>

<Files ~ "^\.ht">
                Order allow,deny
                Deny from all
                Satisfy All
</Files>

</VirtualHost>

And regardless of the script I get:

::SESSION (debug) activate: checking out the situation
::SESSION (debug) id: no session cookie 'rivetSession'
::SESSION (debug) activate: new session, reason 'no_cookie'
::SESSION (debug) get_entropy_bytes: returning 'e978a8ca70f1890a874a'
::SESSION (debug) gen_session_id - feeding this to md5: 
'12946631424269354032127.0.0.11294663142some random 
stringe978a8ca70f1890a874a'
::SESSION (debug) create_session: ip 127.0.0.1, id 
'8DF5C83A062ACB5922CFC89EEA758E7D'

------------------------------------------------------------------------
Cannot manipulate headers - already sent
    invoked from within
"headers add $cookieKey $cookieValue"
    ("set" arm line 18)
    invoked from within
"switch -- $cmd {
        "set" {
            set value [lindex $args 0]
            set args  [lrange $args 1 end]
            import_keyvalue_pairs params $args

            if {[regex..."
    (procedure "cookie" line 4)
    invoked from within
"cookie set $cookieName $value  -path $cookiePath  -minutes $cookieLifetime  -secure 
$cookieSecure"
    (object "::SESSION" method "::Session::set_session_cookie" body line 2)
    invoked from within
"set_session_cookie $id"
    (object "::SESSION" method "::Session::activate" body line 23)
    invoked from within
"SESSION activate"
------------------------------------------------------------------------

*OUTPUT BUFFER:*


SESSION activate
namespace eval request {
puts -nonewline ""


puts "Hello world!";


puts -nonewline "

"

}