Undefined index: upshrink (template error cripples forum)

[Conservationist]

This error showed up and crippled our forum, which is :

SMF File   Your Version   Current Version
SMF Package   SMF 1.1.14   SMF 1.1.14
Sources   1.1.14   1.1.14
Admin.php   1.1.6   1.1.6
Akismet.class.php   ??   ??
Akismet.php   ??   ??
BoardIndex.php   1.1.11   1.1.11
Calendar.php   1.1.5   1.1.5
Display.php   1.1.11   1.1.11
DumpDatabase.php   1.1.12   1.1.12
Errors.php   1.1   1.1
Help.php   1.1   1.1
Karma.php   1.1.5   1.1.5
Load.php   1.1.11   1.1.11
LockTopic.php   1.1   1.1
LogInOut.php   1.1.6   1.1.6
ManageAttachments.php   1.1.11   1.1.11
ManageBans.php   1.1.10   1.1.10
ManageBoards.php   1.1.2   1.1.2
ManageCalendar.php   1.1.11   1.1.11
ManageErrors.php   1.1   1.1
ManageMembergroups.php   1.1.4   1.1.4
ManageMembers.php   1.1.11   1.1.11
ManageNews.php   1.1.13   1.1.13
ManagePermissions.php   1.1.11   1.1.11
ManagePosts.php   1.1   1.1
ManageRegistration.php   1.1.10   1.1.10
ManageSearch.php   1.1.12   1.1.12
ManageServer.php   1.1.5   1.1.5
ManageSmileys.php   1.1.12   1.1.12
Memberlist.php   1.1   1.1
MessageIndex.php   1.1   1.1
ModSettings.php   1.1   1.1
Modlog.php   1.1.11   1.1.11
MoveTopic.php   1.1   1.1
News.php   1.1.12   1.1.12
Notify.php   1.1   1.1
PackageGet.php   1.1.12   1.1.12
Packages.php   1.1.11   1.1.11
PersonalMessage.php   1.1.10   1.1.10
Poll.php   1.1.11   1.1.11
Post.php   1.1.11   1.1.11
Printpage.php   1.1   1.1
Profile.php   1.1.11   1.1.11
QueryString.php   1.1.13   1.1.13
Recent.php   1.1.5   1.1.5
Register.php   1.1.10   1.1.10
Reminder.php   1.1.6   1.1.6
RemoveTopic.php   1.1.5   1.1.5
RepairBoards.php   1.1   1.1
Reports.php   1.1   1.1
SSI.php   1.1.13   1.1.13
Search.php   1.1.13   1.1.13
Security.php   1.1.9   1.1.9
SendTopic.php   1.1   1.1
SplitTopics.php   1.1.11   1.1.11
Stats.php   1.1.6   1.1.6
Subs-Auth.php   1.1.11   1.1.11
Subs-Boards.php   1.1.11   1.1.11
Subs-Charset.php   1.1   1.1
Subs-Compat.php   1.1.6   1.1.6
Subs-Graphics.php   1.1.11   1.1.11
Subs-Members.php   1.1.14   1.1.14
Subs-Package.php   1.1.12   1.1.12
Subs-Post.php   1.1.9   1.1.9
Subs-Sound.php   1.1.6   1.1.6
Subs-backup.php   1.1.11   ??
Subs.php   1.1.13   1.1.13
Themes.php   1.1.11   1.1.11
ViewQuery.php   1.1   1.1
Who.php   1.1   1.1
recaptchalib.php   ??   ??
Default Templates   1.1.12   1.1.12
Admin.template.php   1.1.12   1.1.12
Akismet.template.php   ??   ??
BoardIndex.template.php   1.1   1.1
Calendar.template.php   1.1   1.1
Combat.template.php   1.1   1.1
Display.template.php   1.1.12   1.1.12
Errors.template.php   1.1   1.1
Help.template.php   1.1   1.1
Login.template.php   1.1   1.1
ManageAttachments.template.php   1.1.9   1.1.9
ManageBans.template.php   1.1   1.1
ManageBoards.template.php   1.1   1.1
ManageCalendar.template.php   1.1   1.1
ManageMembergroups.template.php   1.1   1.1
ManageMembers.template.php   1.1   1.1
ManageNews.template.php   1.1   1.1
ManagePermissions.template.php   1.1   1.1
ManageSearch.template.php   1.1   1.1
ManageSmileys.template.php   1.1   1.1
Memberlist.template.php   1.1   1.1
MessageIndex.template.php   1.1   1.1
Modlog.template.php   1.1   1.1
MoveTopic.template.php   1.1   1.1
Notify.template.php   1.1   1.1
Packages.template.php   1.1.11   1.1.11
PersonalMessage.template.php   1.1   1.1
Poll.template.php   1.1.2   1.1.2
Post.template.php   1.1.5   1.1.5
Printpage.template.php   1.1   1.1
Profile.template.php   1.1.2   1.1.2
Recent.template.php   1.1.9   1.1.9
Register.template.php   1.1.10   1.1.10
Reminder.template.php   1.1   1.1
Reports.template.php   1.1   1.1
Search.template.php   1.1.1   1.1.1
SendTopic.template.php   1.1   1.1
Settings.template.php   1.1   1.1
SplitTopics.template.php   1.1.11   1.1.11
Stats.template.php   1.1   1.1
Themes.template.php   1.1   1.1
Who.template.php   1.1   1.1
Wireless.template.php   1.1   1.1
Xml.template.php   1.1   1.1
index.template.php   1.1.5   1.1.5
Language Files   1.1.13   1.1.13
Admin.english.php   1.1.13   1.1.13
Errors.english.php   1.1.2   1.1.2
Help.english.php   1.1   1.1
Install.english.php   1.1   1.1
Login.english.php   1.1.2   1.1.2
ManageBoards.english.php   1.1   1.1
ManageCalendar.english.php   1.1   1.1
ManageMembers.english.php   1.1   1.1
ManagePermissions.english.php   1.1   1.1
ManageSmileys.english.php   1.1   1.1
Manual.english.php   1.1   1.1
ModSettings.english.php   1.1.5   1.1.5
Modifications.english.php   1.1   1.1
Packages.english.php   1.1.8   1.1.8
PersonalMessage.english.php   1.1   1.1
Post.english.php   1.1   1.1
Profile.english.php   1.1   1.1
Reports.english.php   1.1   1.1
Search.english.php   1.1   1.1
Settings.english.php   1.1   1.1
Stats.english.php   1.1   1.1
Themes.english.php   1.1   1.1
Who.english.php   1.1   1.1
Wireless.english.php   1.1   1.1
index.english.php   1.1.13   1.1.13
Current Templates   1.1   1.1.12

The fix was in Themes/theme-name/index.template.php:

        //if ($context['user']['is_guest'])
        //      $options['collapse_header'] = $_COOKIE['upshrink'] !== 0;

These were previously not commented out.

Posted as an FYI to others having the same error; I don't have time today to debug the thing further, as I haven't had time to update this forum to 2.0 (obviously a good idea, if possible and compatible with our template, which of course could unleash many more hours of work, hence procrastinated-with-good-cause).