I tryed to update a very large Project from 2.3.2 to 2.4.1.
In error.log there is:
Warning at \sapphire\core\Cookie.php line 33: Cookie 'alc_enc' can't be set. The site started outputting was content at line 60 in C:\workspace\myproject\sapphire\core\model\DataObjectDecorator.php (http://www-lokal.myproject.de/Security/LoginForm)
How I updated:
I deleted jsparty/, cms/ and sapphire/ folders and copied the new cms/ and sapphire/ folders
then I corrected the references from jsparty/ to sapphire/thirdparty/... or cms/thirdparty/...
then I added SWFUpload Module, because it's not part of the core anymore.
then I did some changes like changeing CalendarDateField into DateField with setConfig('showcalendar', true)
and SiteTree->URLSegment into SiteTree->Link()
I have a similar problem - can't login: "Cookie 'alc_enc' can't be set. The site started outputting was content at line 1 in .../mysite/_config.php"
All files are checked (1 row in the _config.php is <?php), no blank rows or spaces in the beginning or end of files.
When try to open /admin/ link, I see the redirect message "Redirecting to /Security/login?BackURL=%2Fadmin%2F... (output started on .../mysite/_config.php, line 1)". Again config.php...