I am using 2.4.5 and I cannot install the subsites module unless I comment out most of those "Object::add_extension(..." lines in the module's _config.php file. If I don;t comment them I get the famous White Screen of Death.

What's THAT all about? I don't want to comment things because I may lose functionality or cause problems for the users down the track, but I can't find any documentation on this, except for a post from about three years ago, that basically said the same thing.

Can anybody help me? Please?

And here's the query that crashes everything

[User Error] Couldn't run query: SELECT "Subsite"."ClassName", "Subsite"."Created", "Subsite"."LastEdited", "Subsite"."Subdomain", "Subsite"."Title", "Subsite"."RedirectURL", "Subsite"."DefaultSite", "Subsite"."Theme", "Subsite"."Domain", "Subsite"."IsPublic", "Subsite"."FaviconID", "Subsite"."ID", CASE WHEN "Subsite"."ClassName" IS NOT NULL THEN "Subsite"."ClassName" ELSE 'Subsite' END AS "RecordClassName" FROM "Subsite" LEFT JOIN `Group` ON (`SubsiteID`=`Subsite`.`ID` OR `SubsiteID` = 0) LEFT JOIN `Group_Members` ON `Group_Members`.`GroupID`=`Group`.`ID` LEFT JOIN `Permission` ON `Group`.`ID`=`Permission`.`GroupID` WHERE (`Group_Members`.`MemberID` = 1 AND `Permission`.`Code` IN ('CMS_ACCESS_CMSMain', 'ADMIN') AND (Subdomain IS NOT NULL OR `Subsite`.ClassName IN ('Subsite_Template')) AND `Subsite`.Title != '') GROUP BY "Subsite"."ClassName", "Subsite"."Created", "Subsite"."LastEdited", "Subsite"."Subdomain", "Subsite"."Title", "Subsite"."RedirectURL", "Subsite"."DefaultSite", "Subsite"."Theme", "Subsite"."Domain", "Subsite"."IsPublic", "Subsite"."FaviconID", "Subsite"."ID", CASE WHEN "Subsite"."ClassName" IS NOT NULL THEN "Subsite"."ClassName" ELSE 'Subsite' END ORDER BY "Title" Unknown column 'SubsiteID' in 'on clause'

Ok, I've realised that the subsites module in the "extensions" section doesn't actually work (so why is it there?) and I need the trunk version from https://github.com/silverstripe/silverstripe-subsites